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Work, Energy and Power PYQs – Physics, SSC & Railway

196 Work, Energy and Power (Physics) questions asked in recent SSC and Railway exams, newest first, with exam, date & shift, answers and solutions.

📚 196 questionsSSC 12 · Railway 184
12
SSC Stenographer 2026 – 10 September 2026 Shift 1 · Numericals on work, energy and power

Q1. A 60 kg man runs up a 15 m high staircase in 30 seconds. What is the average power developed by him (take g = 10 m/s²)?

  1. (a) 300 W
  2. (b) 350 W
  3. (c) 100 W
  4. (d) 250 W
Answer & solution

Answer: (a) 300 W

Answer: Option 1 — 300 W
Average power = work ÷ time = mgh ÷ t.
Work = 60 × 10 × 15 = 9,000 J, so power = 9,000 ÷ 30 = 300 W.
Revision note — Work, energy and power
• Work = force × displacement in the direction of the force; SI unit joule (J), and 1 J = 1 N m.
• Work done in climbing a height h against gravity equals the gain in potential energy, mgh.
• Power is the rate of doing work, P = W ÷ t; SI unit watt (W), and 1 W = 1 J/s.
• Power can also be written as P = F × v (force × velocity), which gives the same unit.
• 1 horsepower = 746 W. The commercial unit of energy is the kilowatt-hour, and 1 kWh = 3.6 × 10⁶ J.
• In a staircase problem only the vertical height counts — the horizontal run does no work against gravity.
Do not mix these up
• Work vs power — work is the total energy transferred (joule); power is how fast it is transferred (watt = joule per second).
• Watt vs watt-hour — the watt measures power; the watt-hour and the kilowatt-hour measure energy.
Also asked from this topic: the power of a 50 kg girl climbing a 5 m rope in 25 s (98 W, g = 9.8 m/s²); the quantity given by force × velocity (power); one kilowatt-hour in joules (3.6 × 10⁶ J).
RRB Group D 2025-26 – 25 August 2026 Shift 1 · Work and its sign

Q2. A force of 20 N acts opposite to the displacement of 5 m. What is the work done by the force?

  1. (a) –100 J
  2. (b) +25 J
  3. (c) 0 J
  4. (d) +100 J
Answer & solution

Answer: (a) –100 J

Correct Answer:
Correct Answer: Option 1 – –100 J
Explanation:
Work done, W = F × d × cos(θ). Here the force actsopposite
to displacement, so θ = 180°, and cos(180°) = –1. W = 20 N × 5 m × (–1) =–100 J. The negative sign indicates the force does negative work (it opposes the motion, e.g., friction or retarding force).
Important Facts:
• Work is positive when force and displacement are in the same direction.
• Work is zero when force is perpendicular to displacement.
• Work is negative when force opposes displacement, as in this case.
RRB Group D 2025-26 – 25 August 2026 Shift 1 · Kinetic energy

Q3. A bullet and a ball have the same kinetic energy, but the bullet has much less mass than the ball. Which statement about their speeds is correct?

  1. (a) The ball moves much faster than the bullet
  2. (b) Both move at the same speed
  3. (c) Both bullet and ball stay at rest
  4. (d) The bullet moves much faster than the ball
Answer & solution

Answer: (d) The bullet moves much faster than the ball

Correct Answer:
Correct Answer: Option 4 – The bullet moves much faster than the ball
Explanation:
Kinetic energy, KE = ½mv². For the same KE, if mass (m) is much smaller (as with the bullet), the velocity (v) must be much larger to compensate, since v ∝ 1/√m for a fixed KE. Thus the light bullet must travel at a much higher speed than the heavier ball to have the same kinetic energy.
Important Facts:
• This is why bullets, despite tiny mass, are extremely fast and destructive.
• KE depends on the square of velocity, making speed the dominant factor for low-mass objects.
RRB Group D 2025-26 – 25 August 2026 Shift 2 · Power and its units (watt, horsepower)

Q4. If the power of an engine is doubled while the time remains constant, the work done:

  1. (a) becomes four times
  2. (b) becomes half
  3. (c) remains the same
  4. (d) becomes double
Answer & solution

Answer: (d) becomes double

Correct Answer:
Correct Answer: Option 4 – becomes double
Explanation:
Power is defined as P = Work done / Time (P = W/t), so W = P × t. If time (t) is kept constant and power (P) is doubled, then Work done (W) also becomesdouble, since W is directly proportional to P at constant t.
RRB Group D 2025-26 – 25 August 2026 Shift 2 · Numericals on work, energy and power

Q5. A motor performs 1875 J of work in 3 seconds. What is its power output?

  1. (a) 210 W
  2. (b) 5625 W
  3. (c) 2810 W
  4. (d) 625 W
Answer & solution

Answer: (d) 625 W

Correct Answer:
Correct Answer: Option 4 – 625 W
Explanation:
Power = Work done / Time = 1875 J / 3 s =625 W.
RRB Group D 2025-26 – 25 August 2026 Shift 3 · Numericals on work, energy and power

Q6. An object moving with kinetic energy 800 J experiences a net work of −600 J. What happens to the object?

  1. (a) It moves with half speed
  2. (b) It stops moving
  3. (c) It doubles its speed
  4. (d) It continues with same speed
Answer & solution

Answer: (a) It moves with half speed

Correct Answer:
Correct Answer: Option 1 – It moves with half speed
Explanation:
Final KE = 800 + (−600) = 200 J. Since KE ∝ v², the ratio of final to initial KE is 200/800 = 1/4, so v_final/v_initial = √(1/4) = 1/2. The object continues moving but at half its original speed.
Important Facts:
• Work-energy theorem: Work done = change in kinetic energy.
• Negative work means energy is being removed from the object (e.g., by friction or an opposing force).
• KE is proportional to the square of speed, not speed directly.
RRB Group D 2025-26 – 25 August 2026 Shift 3 · Numericals on work, energy and power

Q7. A constant force acts on an object and does 250 J of work while moving it through a distance of 25 m in the direction of the force. What is the magnitude of the force?

  1. (a) 25 N
  2. (b) 20 N
  3. (c) 15 N
  4. (d) 10 N
Answer & solution

Answer: (d) 10 N

Correct Answer:
Correct Answer: Option 4 – 10 N
Explanation:
Work done, W = F × d. Given W = 250 J and d = 25 m, so F = W/d = 250/25 = 10 N.
Important Facts:
• This formula applies when the force acts in the same direction as the displacement.
• SI unit of work is the joule (J), and of force is the newton (N).
RRB Group D 2025-26 – 21 August 2026 Shift 1 · Numericals on work, energy and power

Q8. Student A takes 20 seconds, while student B takes 40 seconds to complete the same amount of work. Which of the following statements is correct in connection to A and B?

  1. (a) Student B has double the power of Student A
  2. (b) Student B has done more work
  3. (c) Both students have the same power
  4. (d) Student A has double the power of Student B
Answer & solution

Answer: (d) Student A has double the power of Student B

Explanation:
Power = Work done / Time taken. For the same amount of work, power is inversely proportional to time. Student A takes 20 s and B takes 40 s, so Power(A)/Power(B) = 40/20 = 2. Hence A has double the power of B.
Correct Answer: Option 4 – Student A has double the power of Student B
RRB Group D 2025-26 – 21 August 2026 Shift 1 · Work and its sign

Q9. A constant force acts on an object and causes it to move in the same direction as the force. How is the work done by the force calculated?

  1. (a) Work is calculated by multiplying force and displacement
  2. (b) Work is calculated by dividing force by displacement
  3. (c) Work is calculated by adding force and displacement
  4. (d) Work is calculated by multiplying force and time
Answer & solution

Answer: (a) Work is calculated by multiplying force and displacement

Explanation:
When a constant force displaces an object in the same direction as the force, the work done is given by the product of force and displacement: W = F × s.
Correct Answer: Option 1 – Work is calculated by multiplying force and displacement
RRB Group D 2025-26 – 21 August 2026 Shift 2 · Simple machines and levers

Q10. An ideal inclined plane is 20 m long and raises a load through a vertical height of 4 m. Compared to lifting the load straight up, the effort required to move the load up the plane is ________.

  1. (a) Equal to the load
  2. (b) One-fourth of the load
  3. (c) One-fifth of the load
  4. (d) One-half of the load
Answer & solution

Answer: (c) One-fifth of the load

Correct Answer:
Correct Answer: Option 3 – One-fifth of the load
Explanation:
For an ideal (frictionless) inclined plane, mechanical advantage = length of incline / height = 20 m / 4 m = 5. Since MA = Load/Effort, Effort = Load/5, i.e., one-fifth of the load.
RRB Group D 2025-26 – 21 August 2026 Shift 3 · Kinetic energy

Q11. A student claims that a stationary object has kinetic energy because it has mass. Evaluate this statement.

  1. (a) The statement is incorrect because kinetic energy requires motion
  2. (b) The statement is correct only for objects on Earth
  3. (c) The statement is incorrect because only energy in motion counts as potential energy
  4. (d) The statement is correct because all objects with mass have kinetic energy
Answer & solution

Answer: (a) The statement is incorrect because kinetic energy requires motion

Correct Answer:
Correct Answer: Option 1 – The statement is incorrect because kinetic energy requires motion
Explanation:
Kinetic energy is given by KE = ½mv². For a stationary object, v = 0, so KE = 0 regardless of mass. Kinetic energy depends onmotion, not merely mass.
Important Facts:
• A stationary object at a height can possess potential energy, not kinetic energy.
RRB Group D 2025-26 – 21 August 2026 Shift 3 · Numericals on work, energy and power

Q12. A toy car of mass 0.5 kg moves with speed 2 m/s, Its kinetic energy is:

  1. (a) 1 J
  2. (b) 2 J
  3. (c) 2.5 J
  4. (d) 0.5 J
Answer & solution

Answer: (a) 1 J

Correct Answer:
Correct Answer: Option 1 – 1 J
Explanation:
KE = ½mv² = ½ × 0.5 kg × (2 m/s)² = ½ × 0.5 × 4 =1 J.
Important Facts:
• Kinetic energy increases with the square of velocity, so doubling speed quadruples KE.
RRB Group D 2025-26 – 20 August 2026 Shift 1 · Simple machines and levers

Q13. The force applied by a person to operate a machine is known as _______.

  1. (a) Load
  2. (b) Effort
  3. (c) Fulcrum
  4. (d) Resistance
Answer & solution

Answer: (b) Effort

Correct Answer:
Correct Answer: Option 2 – Effort
Explanation:
In a simple machine, the force applied by the user to do work is called theeffort, while the resistive force overcome by the machine (e.g., the weight to be lifted) is called theload.
Important Facts:
• Fulcrum is the fixed pivot point about which a lever turns.
• Mechanical advantage = Load / Effort.
RRB Group D 2025-26 – 20 August 2026 Shift 1 · Numericals on work, energy and power

Q14. If a 4 kg object is moving at 3 m/s and another 2 kg object is moving at 6 m/s, which one has more kinetic energy?

  1. (a) Both objects have equal kinetic energy
  2. (b) Neither object has kinetic energy
  3. (c) The 4 kg object moving at 3 m/s
  4. (d) The 2 kg object moving at 6 m/s
Answer & solution

Answer: (d) The 2 kg object moving at 6 m/s

Correct Answer:
Correct Answer: Option 4 – The 2 kg object moving at 6 m/s
Explanation:
Kinetic Energy = ½mv².For the 4 kg object at 3 m/s: KE = ½ × 4 × 3² = ½ × 4 × 9 =18 J
.For the 2 kg object at 6 m/s: KE = ½ × 2 × 6² = ½ × 2 × 36 =36 J
.Since 36 J > 18 J, the 2 kg object moving at 6 m/s has more kinetic energy.
Important Facts:
• Kinetic energy depends on the square of velocity, so velocity has a greater effect on KE than mass.
• SI unit of kinetic energy is the Joule (J).
RRB Group D 2025-26 – 20 August 2026 Shift 2 · Simple machines and levers

Q15. While operating a lever, which part serves as the fixed point around which the lever rotates?

  1. (a) Effort arm
  2. (b) Effort
  3. (c) Load
  4. (d) Fulcrum
Answer & solution

Answer: (d) Fulcrum

Correct Answer:
Correct Answer: Option 4 – Fulcrum
Explanation:
The fulcrum is the fixed pivot point about which a lever rotates when effort is applied to move a load.
Important Facts:
• Effort is the force applied; load is the resistance/weight to be overcome; effort arm is the distance from the fulcrum to the point of effort application.
RRB Group D 2025-26 – 20 August 2026 Shift 2 · Simple machines and levers

Q16. Which statement best describes the mechanical advantage of a simple machine?

  1. (a) The ratio of the load lifted to the effort applied
  2. (b) The amount of work done by the machine
  3. (c) The energy supplied to the machine
  4. (d) The rate at which the machine performs work
Answer & solution

Answer: (a) The ratio of the load lifted to the effort applied

Correct Answer:
Correct Answer: Option 1 – The ratio of the load lifted to the effort applied
Explanation:
Mechanical Advantage (MA) = Load / Effort. It indicates how much a simple machine multiplies the applied effort.
RRB Group D 2025-26 – 20 August 2026 Shift 3 · Numericals on work, energy and power

Q17. An object of mass 12.5 kg is lifted to a height of 8 m. (Take g = 10 m/s².) Its potential energy is _______.

  1. (a) 100 J
  2. (b) 1250 J
  3. (c) 800 J
  4. (d) 1000 J
Answer & solution

Answer: (d) 1000 J

Correct Answer:
Option 4 – 1000 J
Explanation:
Potential Energy = mgh = 12.5 × 10 × 8 =1000 J.
RRB Group D 2025-26 – 20 August 2026 Shift 3 · Numericals on work, energy and power

Q18. Object A (3 kg) moves at 4 m/s, and object B (6 kg) moves at 2 m/s. Which object has greater kinetic energy?

  1. (a) Object B
  2. (b) Cannot be determined
  3. (c) Both have equal kinetic energy
  4. (d) Object A
Answer & solution

Answer: (d) Object A

Correct Answer:
Option 4 – Object A
Explanation:
Kinetic Energy = ½mv². Object A: ½ × 3 × 4² = ½ × 3 × 16 = 24 J. Object B: ½ × 6 × 2² = ½ × 6 × 4 = 12 J. Since 24 J > 12 J,Object Ahas greater kinetic energy.
RRB Group D 2025-26 – 19 August 2026 Shift 1 · Simple machines and levers

Q19. During an experiment, a student gradually lowers the angle of an ideal ramp while pulling a toy cart to the same height. What observation should the student expect?

  1. (a) The force required remains constant.
  2. (b) The cart gains less potential energy.
  3. (c) The force required decreases.
  4. (d) The force required increases.
Answer & solution

Answer: (c) The force required decreases.

Correct Answer:
Correct Answer: Option 3 – The force required decreases.
Explanation:
For an ideal (frictionless) ramp, the work done to raise the cart to a fixed height is constant:Work = Force × distance along the ramp = mgh(a fixed value). As the ramp angle is lowered, the length of the incline needed to reach the same heightincreases, so theforce required decreasesproportionally (a mechanical advantage effect of the inclined plane).
Important Facts:
• An inclined plane is a simple machine: lower angle → longer path → less force needed for the same work.
• The work done and the potential energy gained (mgh) remain the same regardless of the ramp's angle (ideal case).
RRB Group D 2025-26 – 19 August 2026 Shift 1 · Conservation and transformation of energy

Q20. A ball rolls down a hill without any friction and reaches the bottom. Which of the following statements best describes how energy is transformed as the ball moves?

  1. (a) As the ball rolls, its total energy increases
  2. (b) The ball's potential energy decreases while its kinetic energy increases
  3. (c) As the ball moves, both potential and kinetic energy increase
  4. (d) As the ball moves downward, its kinetic energy keeps decreasing
Answer & solution

Answer: (b) The ball's potential energy decreases while its kinetic energy increases

Correct Answer:
Correct Answer: Option 2 – The ball's potential energy decreases while its kinetic energy increases
Explanation:
By the law of conservation of energy, in the absence of friction, the ball'stotal mechanical energy remains constant. As the ball rolls down, itsheight decreases, so itspotential energy decreases, and this lost potential energy is converted intokinetic energy, which correspondinglyincreases.
Important Facts:
• Total mechanical energy (PE + KE) stays constant in the absence of friction.
• PE = mgh decreases as height decreases; KE = ½mv² increases as speed increases.
RRB Group D 2025-26 – 19 August 2026 Shift 2 · Simple machines and levers

Q21. Two machines lift the same load. Machine P requires an effort of 100 N, while Machine Q requires an effort of 50 N. Which machine has the greater mechanical advantage?

  1. (a) Both machines are equally efficient
  2. (b) Machine Q
  3. (c) Machine P
  4. (d) Cannot be determined
Answer & solution

Answer: (b) Machine Q

Correct Answer:
Correct Answer: Option 2 – Machine Q
Explanation:
Mechanical Advantage (MA) = Load / Effort. Since both machines lift the same load, the machine requiringless efforthas thegreater MA. Machine Q needs only 50 N compared to Machine P's 100 N, so Machine Q has double the mechanical advantage of Machine P.
Important Facts:
• MA is inversely proportional to the effort required for a fixed load.
• A higher MA means the machine multiplies the applied force more effectively.
RRB Group D 2025-26 – 19 August 2026 Shift 2 · Simple machines and levers

Q22. What is the primary purpose of a simple machine?

  1. (a) To create energy
  2. (b) To reduce the total work done in a task
  3. (c) To increase the weight of an object
  4. (d) To make work easier by changing the magnitude or direction of a force
Answer & solution

Answer: (d) To make work easier by changing the magnitude or direction of a force

Correct Answer:
Correct Answer: Option 4 – To make work easier by changing the magnitude or direction of a force
Explanation:
A simple machine (like a lever, pulley, or inclined plane) does not create energy or reduce the total work done (in fact, due to friction, real machines require slightly more input work than useful output work). Its purpose is tomake work more convenientby allowing a change in the magnitude of the applied force (trading force for distance, or vice versa) and/or the direction in which the force is applied.
Important Facts:
• Work-energy principle: machines cannot create energy (violates conservation of energy) — they only transform how force and displacement are applied.
• Ideal machines conserve work input = work output; real machines have output work less than input due to friction.
RRB Group D 2025-26 – 19 August 2026 Shift 3 · Simple machines and levers

Q23. A worker has to raise a heavy load to a certain height. Four ideal machines are available. Their mechanical advantages are given below:Machine P: MA = 0.5Machine Q: MA = 0.8Machine R: MA = 2Machine S: MA = 4Assume all machines are frictionless and the load must be lifted through the same vertical height.Which of the following statements is correct?

  1. (a) Machines R and S require the same effort since the load is unchanged.
  2. (b) Machine P requires the least effort because it has the smallest MA.
  3. (c) Machine S performs less work than the other machines.
  4. (d) Machine S requires the least effort but the effort moves through the greatest distance.
Answer & solution

Answer: (d) Machine S requires the least effort but the effort moves through the greatest distance.

Correct Answer:
Option 4 – Machine S requires the least effort but the effort moves through the greatest distance.
Explanation:
For an ideal (frictionless) machine, Mechanical Advantage (MA) = Load/Effort, and also MA = Velocity Ratio = (distance moved by effort)/(distance moved by load). Since work input = work output for an ideal machine, a machine with thehighest MA (Machine S, MA=4)requires theleast effortto lift the same load, but because effort distance = MA × load distance, its effort must move through thegreatest distanceto do the same amount of work.
Important Facts:
• For an ideal machine, Work input = Work output (Effort × effort-distance = Load × load-distance).
• Higher MA → lower effort required but effort must move a proportionally greater distance.
Correct Answer: Option 4 – Machine S requires the least effort but the effort moves through the greatest distance.
RRB Group D 2025-26 – 19 August 2026 Shift 3 · Kinetic energy

Q24. When an object of mass m is moving with a velocity v, its kinetic energy is K, what will be its kinetic energy if its velocity is doubled?

  1. (a) 3K
  2. (b) 2K
  3. (c) K
  4. (d) 4K
Answer & solution

Answer: (d) 4K

Correct Answer:
Option 4 – 4K
Explanation:
Kinetic energy is given by KE = ½mv². If the velocity is doubled (v′ = 2v), the new kinetic energy becomes: KE′ = ½m(2v)² = ½m·4v² = 4(½mv²) =4K.
Important Facts:
• Kinetic energy is directly proportional to the square of velocity.
• Kinetic energy is a scalar quantity, measured in joules (J).
Correct Answer: Option 4 – 4K
RRB Group D 2025-26 – 18 August 2026 Shift 1 · Power and its units (watt, horsepower)

Q25. A factory manager is comparing two machines that perform the same task. Machine A takes more time to complete the task than Machine B. Based on the definition of power, which factor should the manager consider to determine which machine is more powerful?

  1. (a) The rate at which each machine does work
  2. (b) The mass of each machine
  3. (c) The amount of energy used by each machine
  4. (d) The total work done by each machine
Answer & solution

Answer: (a) The rate at which each machine does work

Definition of power
Power is defined as therate of doing work, i.e., Power = Work done / Time taken.
Since both machines perform the same task (same work), the one that takes less time has a higher rate of doing work, hence is more powerful. The relevant factor is therefore the rate at which each machine does work, not the total work, mass, or energy consumed alone.
Correct Answer: The rate at which each machine does work
RRB Group D 2025-26 – 18 August 2026 Shift 1 · Numericals on work, energy and power

Q26. A force of 7 N acts on an object, displacing it through 8 m in the direction of the force. What is the work done?

  1. (a) 15 J
  2. (b) 1 J
  3. (c) 56 J
  4. (d) 27 J
Answer & solution

Answer: (c) 56 J

Work done by a force
Work done, W = Force × displacement (when force and displacement are in the same direction).
W = 7 N × 8 m =56 J.
Correct Answer: 56 J
RRB Group D 2025-26 – 18 August 2026 Shift 2 · Numericals on work, energy and power

Q27. For the same amount of work, the time taken by Machine A is one-half that of Machine B. What is the ratio of the power of Machine A to that of Machine B?

  1. (a) 1 : 2
  2. (b) 2 : 1
  3. (c) 1 : 1
  4. (d) 4 : 1
Answer & solution

Answer: (b) 2 : 1

Power Ratio
Power = Work / Time. For the same amount of work W:
• Time taken by A, t_A = (1/2) t_B
• P_A = W / t_A, P_B = W / t_B
• P_A / P_B = t_B / t_A = t_B / (t_B/2) = 2
So the ratio of power of A to B is2 : 1.
Correct Answer: 2 : 1
RRB Group D 2025-26 – 18 August 2026 Shift 2 · Work and its sign

Q28. When lifting an object upwards, the work done by the force of gravity is considered negative because _____________.

  1. (a) Force of gravity only does positive work on falling objects
  2. (b) The object is displaced upward, opposite to the downward force of gravity
  3. (c) The force of gravity is constant
  4. (d) The net force on the object is zero
Answer & solution

Answer: (b) The object is displaced upward, opposite to the downward force of gravity

Work Done Against Gravity
Work done = Force × displacement × cos(θ), where θ is the angle between force and displacement.
When lifting an object, the displacement is upward while the force of gravity acts downward — these are in opposite directions (θ = 180°), making cos(θ) = −1, so the work done by gravity isnegative.
Correct Answer: The object is displaced upward, opposite to the downward force of gravity
RRB Group D 2025-26 – 18 August 2026 Shift 3 · Simple machines and levers

Q29. A machine lifts a 1500 N load using an effort of 250 N. Due to friction, the effort required later becomes 375 N while lifting the same load. Which statement is correct?

  1. (a) Load increased by 50%
  2. (b) Effort decreased by 50%
  3. (c) Load and effort both increased by 50%
  4. (d) Effort increased by 50% while load remained unchanged
Answer & solution

Answer: (d) Effort increased by 50% while load remained unchanged

Concept: Effect of Friction on a Machine
Theloadlifted by a machine is 1500 N in both cases — this does not change. Friction affects only theeffortrequired, since some of the input effort is used to overcome friction rather than to do useful work on the load.
• Initial effort = 250 N (ideal, frictionless case)
• Later effort (with friction) = 375 N
• Increase in effort = 375 − 250 = 125 N
• Percentage increase = (125/250) × 100 = 50%
So the effort increased by 50% due to friction, while the load lifted (1500 N) remained exactly the same.
Correct Answer: Effort increased by 50% while load remained unchanged
RRB Group D 2025-26 – 18 August 2026 Shift 3 · Commercial unit of energy (kWh)

Q30. A device uses 1 kilowatt (kW) of power for 1 hour. How much energy does it consume?

  1. (a) 1 joule (J)
  2. (b) 1 kilowatt hour (kWh)
  3. (c) 1 watt hour (Wh)
  4. (d) 1 kilowatt (kW)
Answer & solution

Answer: (b) 1 kilowatt hour (kWh)

Concept: Electrical Energy Units
Electrical energy consumed = Power × Time. A device using 1 kilowatt of power for 1 hour consumes exactly1 kilowatt-hour (kWh)of energy — this is the standard commercial unit of electrical energy, commonly known as 1 'unit' of electricity.
Correct Answer: 1 kilowatt hour (kWh)
RRB Group D 2025-26 – 18 August 2026 Shift 3 · Conservation and transformation of energy

Q31. When a flashlight is turned on, what energy change occurs?

  1. (a) Light energy changes to sound energy
  2. (b) Light energy changes to chemical energy
  3. (c) Chemical energy changes to sound energy
  4. (d) Chemical energy changes to light energy
Answer & solution

Answer: (d) Chemical energy changes to light energy

Concept: Energy Transformation in a Flashlight
A flashlight (torch) uses a battery, which stores chemical energy. When switched on, this chemical energy is converted into electrical energy which then powers the bulb/LED, producing light. Overall, the net transformation described is:chemical energy → light energy.
Correct Answer: Chemical energy changes to light energy
RRB Group D 2025-26 – 17 August 2026 Shift 1 · Work and its sign

Q32. A force of 300 N acts on an object. If displacement becomes three times larger while force remains constant, work done ____.

  1. (a) becomes three times
  2. (b) becomes one-third
  3. (c) becomes nine times
  4. (d) remains same
Answer & solution

Answer: (a) becomes three times

Work Done and Displacement
Work done,W = F × d, where F is the applied force and d is the displacement in the direction of the force.
Since the force (300 N) remainsconstantand the displacement becomes three times larger, W = F × (3d) = 3 × (F × d). So the new work done isthree timesthe original work done.
Correct Answer: becomes three times
RRB Group D 2025-26 – 17 August 2026 Shift 1 · Numericals on work, energy and power

Q33. A force of 45 N causes an object to move 3 m in the direction of the force. Calculate the work done.

  1. (a) 145 J
  2. (b) 125 J
  3. (c) 135 J
  4. (d) 155 J
Answer & solution

Answer: (c) 135 J

Calculating Work Done
Work done, W = F × d = 45 N × 3 m =135 J.
Correct Answer: 135 J
RRB Group D 2025-26 – 17 August 2026 Shift 2 · Potential energy

Q34. An object is placed at a certain height above the ground. Which form of energy does it possess due to its position?

  1. (a) Chemical energy
  2. (b) Thermal energy
  3. (c) Potential energy
  4. (d) Kinetic energy
Answer & solution

Answer: (c) Potential energy

Energy Due to Position
An object raised to a height above the ground possessespotential energy(specifically gravitational potential energy), given by PE = mgh, due to its position in a gravitational field.
• Kinetic energy is due to motion, not position.
• Chemical and thermal energy are unrelated to positional height.
Correct Answer: Potential energy
RRB Group D 2025-26 – 17 August 2026 Shift 2 · Work and its sign

Q35. An object is moving eastward. Which force will definitely do negative work on it?

  1. (a) A force acting eastward
  2. (b) A force acting downward
  3. (c) A force acting westward
  4. (d) A force acting upward
Answer & solution

Answer: (c) A force acting westward

Negative Work by a Force
Work done by a force is W = F·d·cosθ, where θ is the angle between force and displacement. Work is negative when the force has a component opposite to the direction of displacement. Since the object moves eastward, aforce acting westward(directly opposite to motion, θ = 180°) will definitely do negative work.
• A force acting eastward (same direction) does positive work.
• Forces acting downward or upward are perpendicular to eastward motion (θ = 90°), doing zero work, not negative work.
Correct Answer: A force acting westward
RRB Group D 2025-26 – 17 August 2026 Shift 3 · Numericals on work, energy and power

Q36. A stone of mass 0.5 kg is moving with a speed of 8 m/s. Its kinetic energy is ________.

  1. (a) 16 J
  2. (b) 64 J
  3. (c) 128 J
  4. (d) 32 J
Answer & solution

Answer: (a) 16 J

Kinetic Energy Calculation
Kinetic energy is given by KE = (1/2) m v².
• Mass m = 0.5 kg, speed v = 8 m/s
• KE = 0.5 × 0.5 × 8² = 0.5 × 0.5 × 64 = 16 J
Correct Answer: 16 J
RRB Group D 2025-26 – 17 August 2026 Shift 3 · Conservation and transformation of energy

Q37. Which of the following is an example of chemical energy?

  1. (a) Energy from a spinning wheel
  2. (b) Energy stored in food
  3. (c) Energy from a stretched rubber band
  4. (d) Energy from moving objects
Answer & solution

Answer: (b) Energy stored in food

Example of Chemical Energy
Chemical energy is energy stored in the bonds of chemical compounds, released during chemical reactions (like digestion or combustion).
• Energy stored in food is chemical energy, released when food is broken down (metabolised) in the body.
• A spinning wheel or moving object has kinetic energy; a stretched rubber band has elastic potential energy — none of these are chemical energy.
Correct Answer: Energy stored in food
RRB Group D 2025-26 – 14 August 2026 Shift 1 · Conservation and transformation of energy

Q38. What form of energy does a glowing bulb emit?

  1. (a) Sound energy
  2. (b) Light energy
  3. (c) Chemical energy
  4. (d) Gravitational energy
Answer & solution

Answer: (b) Light energy

Answer: Option 2 – Light energy.
• A glowing bulb chiefly emitslight energy(and some heat).
RRB Group D 2025-26 – 14 August 2026 Shift 1 · Conservation and transformation of energy

Q39. A diver jumps off a diving board into a pool. At the moment just before entering the water, which statement best applies according to the law of conservation of energy?

  1. (a) The diver’s loss in potential energy equals the gain in kinetic energy
  2. (b) The diver’s total energy increases during the fall
  3. (c) The diver loses energy during the fall to the surroundings
  4. (d) The diver’s potential energy stays the same throughout
Answer & solution

Answer: (a) The diver’s loss in potential energy equals the gain in kinetic energy

Answer: Option 1 – The diver's loss in PE equals the gain in KE.
• By conservation of energy,PE lost = KE gained(ignoring losses).
RRB Group D 2025-26 – 14 August 2026 Shift 2 · Numericals on work, energy and power

Q40. A trolley is pulled along a straight track by a constant force of 40 N. If the work done on the trolley is 240 J, what distance does the trolley travel?

  1. (a) 4 m
  2. (b) 6 m
  3. (c) 12 m
  4. (d) 2 m
Answer & solution

Answer: (b) 6 m

Answer: Option 2 – 6 m.
• W = F × s ⇒ s = 240/40 =6 m.
RRB Group D 2025-26 – 14 August 2026 Shift 2 · Numericals on work, energy and power

Q41. If a force of 1 N displaces an object by 1 m along the line of force, the work done is:

  1. (a) 10 J
  2. (b) 0.1 J
  3. (c) 0.5 J
  4. (d) 1 J
Answer & solution

Answer: (d) 1 J

Answer: Option 4 – 1 J.
• W = F × s = 1 N × 1 m =1 J.
RRB Group D 2025-26 – 14 August 2026 Shift 3 · Simple machines and levers

Q42. A rescue team uses a long steel rod as a lever to lift a heavy concrete slab. To minimize the force required, where should the fulcrum be positioned?

  1. (a) Away from both the slab and the effort
  2. (b) Exactly halfway between the slab and the effort
  3. (c) Near the slab being lifted
  4. (d) Near the point where the force is applied
Answer & solution

Answer: (c) Near the slab being lifted

Answer: Option 3 – Near the slab being lifted.
• Placing the fulcrumnear the loadincreases the effort arm, reducing the force needed.
RRB Group D 2025-26 – 14 August 2026 Shift 3 · Power and its units (watt, horsepower)

Q43. Which statement about power is correct?

  1. (a) Power measures how quickly work is done.
  2. (b) Power depends only on force.
  3. (c) Power is independent of time.
  4. (d) Power and work have the same SI unit.
Answer & solution

Answer: (a) Power measures how quickly work is done.

Answer: Option 1 – Power measures how quickly work is done.
•Power = work/time– the rate of doing work.
RRB Group D 2025-26 – 13 August 2026 Shift 1 · Numericals on work, energy and power

Q44. The work done to increase the kinetic energy of a 4 kg object from 50 J to 98 J is:

  1. (a) 24.5 J
  2. (b) 48 J
  3. (c) 52 J
  4. (d) 148 J
Answer & solution

Answer: (b) 48 J

Answer: Option 2 – 48 J.
• Work done = change in KE = 98 − 50 =48 J.
RRB Group D 2025-26 – 13 August 2026 Shift 1 · Potential energy

Q45. A box is raised to the same height either by lifting it vertically or by pushing it up an ideal inclined plane. Which quantity is the same in both cases?

  1. (a) Mechanical advantage of the method used
  2. (b) Potential energy gained by the box
  3. (c) Effort applied
  4. (d) Distance moved by the box
Answer & solution

Answer: (b) Potential energy gained by the box

Answer: Option 2 – Potential energy gained by the box.
• For the same height, thegain in potential energy (mgh)is the same, regardless of the path.
RRB Group D 2025-26 – 13 August 2026 Shift 2 · Potential energy

Q46. If you lift a book and place it on a shelf, what happens to its energy?

  1. (a) It loses all energy
  2. (b) It gains kinetic energy
  3. (c) Its potential energy increases
  4. (d) Its thermal energy increases
Answer & solution

Answer: (c) Its potential energy increases

Answer: Option 3 – Its potential energy increases.
• Raising the book increases its height, so itspotential energy increases.
RRB Group D 2025-26 – 13 August 2026 Shift 2 · Commercial unit of energy (kWh)

Q47. Which expression correctly represents the commercial unit of electrical energy in terms of joules?

  1. (a) 1 kilowatt hour = 3.6 × 10⁶ joules
  2. (b) 1 kilowatt hour = 1.6 × 10⁶ joules
  3. (c) 1 kilowatt hour = 1000 joules
  4. (d) 1 kilowatt hour = 360 joules
Answer & solution

Answer: (a) 1 kilowatt hour = 3.6 × 10⁶ joules

Answer: Option 1 – 1 kWh = 3.6 × 10⁶ J.
• 1 kWh = 1000 W × 3600 s =3.6 × 10⁶ J.
RRB Group D 2025-26 – 13 August 2026 Shift 3 · Power and its units (watt, horsepower)

Q48. A worker performs a task. Which of the following statements about power are correct?1. If work remains constant and time increases, power decreases.2. If time remains constant and work increases, power increases.3. Power is directly proportional to work done.4. Power is inversely proportional to time taken.

  1. (a) 1, 2, 3 and 4
  2. (b) 1, 3 and 4 only
  3. (c) 2 and 4 only
  4. (d) 1, 2 and 3 only
Answer & solution

Answer: (a) 1, 2, 3 and 4

Answer: Option 1 – 1, 2, 3 and 4.
• Power = Work/Time, so P ∝ work, P ∝ 1/time. All four statements are correct.
RRB Group D 2025-26 – 13 August 2026 Shift 3 · Simple machines and levers

Q49. Which of the following is NOT true about simple machines?

  1. (a) They reduce total work done in all cases
  2. (b) They make tasks more convenient
  3. (c) They can reduce the effort required
  4. (d) They can change the direction of force
Answer & solution

Answer: (a) They reduce total work done in all cases

Answer: Option 1 – They reduce total work done in all cases.
• Machines do NOT reduce total work (output work ≤ input work); they only make tasks convenient. So this statement is NOT true.
RRB Group D 2025-26 – 12 August 2026 Shift 1 · Work and its sign

Q50. A cyclist applies brakes to stop a moving bicycle. The work done by the braking force on the bicycle is _______.

  1. (a) Both positive and negative
  2. (b) Zero
  3. (c) Negative only
  4. (d) Positive only
Answer & solution

Answer: (c) Negative only

Answer: Option 3 – Negative only.
• The braking force acts opposite to the motion, so the work done by it isnegative.
RRB Group D 2025-26 – 12 August 2026 Shift 1 · Potential energy

Q51. A climber is carrying a backpack up a mountain with varying slopes. At which point during the climb is the potential energy of the backpack at its maximum, assuming no energy is lost and the mass remains constant?

  1. (a) At the halfway point up the mountain
  2. (b) At the highest elevation reached during the climb
  3. (c) At the steepest slope of the climb
  4. (d) At the starting position at the mountain base
Answer & solution

Answer: (b) At the highest elevation reached during the climb

Answer: Option 2 – At the highest elevation reached during the climb.
• P.E. = mgh, so it is maximum at thegreatest height.
RRB Group D 2025-26 – 12 August 2026 Shift 2 · Work and its sign

Q52. Which of the following situations correctly illustrates the scientific definition of work in physics?

  1. (a) A person holds a book stationary above their head
  2. (b) A person lifts a box from the floor onto a table
  3. (c) A person pushes against a wall but the wall does not move
  4. (d) A person walks with a backpack at constant speed
Answer & solution

Answer: (b) A person lifts a box from the floor onto a table

Answer: Option 2 – A person lifts a box from the floor onto a table.
• Work is done only with force AND displacement in its direction; lifting a box does both.
RRB Group D 2025-26 – 12 August 2026 Shift 2 · Simple machines and levers

Q53. Which observation would provide the strongest evidence that a machine is a fixed pulley?

  1. (a) The machine stores energy while lifting.
  2. (b) The effort and load move in opposite directions.
  3. (c) The load becomes lighter during lifting.
  4. (d) The applied force is smaller than the load.
Answer & solution

Answer: (b) The effort and load move in opposite directions.

Answer: Option 2 – The effort and load move in opposite directions.
• Afixed pulleyonly changes force direction (MA = 1); effort and load move oppositely.
RRB Group D 2025-26 – 12 August 2026 Shift 3 · Simple machines and levers

Q54. A worker is choosing among four levers to lift a heavy concrete block. To reduce the effort required as much as possible, which lever should the worker select?

  1. (a) Effort arm = 40 cm, Load arm = 10 cm
  2. (b) Effort arm = 20 cm, Load arm = 20 cm
  3. (c) Effort arm = 50 cm, Load arm = 25 cm
  4. (d) Effort arm = 30 cm, Load arm = 15 cm
Answer & solution

Answer: (a) Effort arm = 40 cm, Load arm = 10 cm

Answer: Option 1 – Effort arm 40 cm, Load arm 10 cm.
• Mechanical advantage = effort arm/load arm. 40/10 = 4 is the largest ⇒ least effort needed.
RRB Group D 2025-26 – 12 August 2026 Shift 3 · Conservation and transformation of energy

Q55. Which statement best describes the law of conservation of energy?

  1. (a) Energy is used up during physical processes and disappears.
  2. (b) Energy cannot be created or destroyed; it only changes form.
  3. (c) Energy always increases in a closed system.
  4. (d) Energy can be destroyed but not created.
Answer & solution

Answer: (b) Energy cannot be created or destroyed; it only changes form.

Answer: Option 2 – Energy cannot be created or destroyed; it only changes form.
• This is thelaw of conservation of energy.
RRB Group D 2025-26 – 11 August 2026 Shift 1 · Simple machines and levers

Q56. Which of the following best describes a load?

  1. (a) The object being moved or lifted
  2. (b) The energy stored in a system
  3. (c) A machine used for lifting
  4. (d) The force applied downward
Answer & solution

Answer: (a) The object being moved or lifted

Answer: Option 1 – The object being moved or lifted.
• In a machine/lever, theloadis the object (weight) being moved or lifted.
RRB Group D 2025-26 – 11 August 2026 Shift 1 · Simple machines and levers

Q57. A group of students is designing a wheelchair ramp for their school entrance. According to the concept of a simple machine, which modification would make it easier to push a wheelchair to the same height?

  1. (a) Increasing the length of the ramp while keeping its height constant
  2. (b) Adding friction material to the ramp surface to slow down movement
  3. (c) Making the ramp steeper by decreasing its length for the same height
  4. (d) Adding steps instead of a ramp to reach the same height
Answer & solution

Answer: (a) Increasing the length of the ramp while keeping its height constant

Answer: Option 1 – Increasing the length of the ramp while keeping its height constant.
• A longer inclined plane (ramp) for the same height reduces the slope, soless effort/forceis needed to push the wheelchair up.
RRB Group D 2025-26 – 11 August 2026 Shift 2 · Simple machines and levers

Q58. Which quantity indicates the factor by which a simple machine multiplies the applied force?

  1. (a) Efficiency
  2. (b) Velocity ratio
  3. (c) Mechanical advantage
  4. (d) Input work
Answer & solution

Answer: (c) Mechanical advantage

Answer: Option 3 – Mechanical advantage.
•Mechanical advantage= load/effort, the factor by which a machine multiplies the applied force.
RRB Group D 2025-26 – 11 August 2026 Shift 2 · Kinetic energy

Q59. A vehicle of mass M travels at velocity V. If its kinetic energy increases by a factor of 9, how much does its velocity change?

  1. (a) The velocity is tripled
  2. (b) The velocity is doubled
  3. (c) The velocity is increased nine times
  4. (d) The velocity is quadrupled
Answer & solution

Answer: (a) The velocity is tripled

Answer: Option 1 – The velocity is tripled.
• KE ∝ v². If KE becomes 9×, then v² becomes 9× ⇒ v becomes 3× (tripled).
RRB Group D 2025-26 – 11 August 2026 Shift 3 · Numericals on work, energy and power

Q60. A 3 kg stone is thrown vertically upwards with a speed of 8 m/s. What is its kinetic energy at the moment it leaves the thrower's hand?

  1. (a) 96 J
  2. (b) 24 J
  3. (c) 72 J
  4. (d) 48 J
Answer & solution

Answer: (a) 96 J

Answer: Option 1 – 96 J.
• KE = ½mv² = ½ × 3 × 8² = ½ × 3 × 64 =96 J.
RRB Group D 2025-26 – 11 August 2026 Shift 3 · Kinetic energy

Q61. Which physical quantity must be known to calculate the kinetic energy of a moving object?

  1. (a) Mass and time
  2. (b) Mass only
  3. (c) Velocity only
  4. (d) Mass and velocity
Answer & solution

Answer: (d) Mass and velocity

Answer: Option 4 – Mass and velocity.
• KE = ½mv² needs bothmass and velocity.
RRB Group D 2025-26 – 10 August 2026 Shift 1 · Simple machines and levers

Q62. A machine lifts a load of 600 N using an effort of 150 N. What is the mechanical advantage of the machine?

  1. (a) 5
  2. (b) 3
  3. (c) 2
  4. (d) 4
Answer & solution

Answer: (d) 4

Answer: Option 4 — 4
MA = load/effort = 600/150 =4→ Option 4.
RRB Group D 2025-26 – 10 August 2026 Shift 2 · Work and its sign

Q63. For work to be considered done on an object, which two conditions must be met?

  1. (a) The force must be applied for a long time, and the object must be at rest.
  2. (b) A force must act on the object, and the object must move.
  3. (c) The object must be heavy, and the force must be large.
  4. (d) The object must move fast, and the force must be constant.
Answer & solution

Answer: (b) A force must act on the object, and the object must move.

Answer: Option 2 – A force must act on the object, and the object must move.
• Work (W = F × s × cosθ) is done only when aforce actsand the object undergoesdisplacementin the direction of the force.
• No displacement ⇒ no work, whatever the force or time.
RRB Group D 2025-26 – 10 August 2026 Shift 2 · Potential energy

Q64. Which of the following does NOT possess potential energy (with respect to the ground)?

  1. (a) A compressed spring
  2. (b) A stone on the roof
  3. (c) Water stored in a dam
  4. (d) A freely falling body at ground level
Answer & solution

Answer: (d) A freely falling body at ground level

Answer: Option 4 – A freely falling body at ground level.
• Potential energy depends on height (P.E. = mgh). At ground levelh = 0, so P.E. = 0.
• A compressed spring (elastic P.E.), a stone on a roof, and dammed water all possess potential energy.
RRB Group D 2025-26 – 10 August 2026 Shift 3 · Simple machines and levers

Q65. Consider the following statements about a seesaw used in a playground.1. The central support acts as the fulcrum.2. The weight of a child on one side may act as the load.3. The force applied by a child on the opposite side may act as the effort.4. A seesaw is an example of a first-class lever.Which of the above statements are correct?

  1. (a) 1, 2 and 3 only
  2. (b) 1 and 2 only
  3. (c) 1, 2 and 4 only
  4. (d) 1, 2, 3 and 4
Answer & solution

Answer: (d) 1, 2, 3 and 4

Answer: Option 4 – 1, 2, 3 and 4.
• A seesaw is afirst-class lever: fulcrum (central support) lies between the load (weight of one child) and the effort (force by the other child). All four statements are correct.
RRB Group D 2025-26 – 9 August 2026 Shift 1 · Potential energy

Q66. A roller coaster car is at the highest point of its track and is about to descend. If the mass of the car and its passengers is doubled while keeping the height and gravity constant, how does the gravitational potential energy at the top compare to the original scenario?

  1. (a) The gravitational potential energy is doubled
  2. (b) The gravitational potential energy is halved
  3. (c) The gravitational potential energy is unchanged
  4. (d) The gravitational potential energy is quadrupled
Answer & solution

Answer: (a) The gravitational potential energy is doubled

Answer: Option 1 — The gravitational potential energy is doubled
PE = mgh. Doubling mass (h, g constant)doublesPE → Option 1.
RRB Group D 2025-26 – 9 August 2026 Shift 2 · Simple machines and levers

Q67. Consider the following statements about simple machines.1. Help lift heavy loads.2. Can increase the distance through which effort acts.3. May change the direction of force.4. Violate the law of conservation of energy.Which of the above statements are correct?

  1. (a) 2 and 3 only
  2. (b) 1, 2 and 3 only
  3. (c) 1, 2, 3 and 4
  4. (d) 1 and 4 only
Answer & solution

Answer: (b) 1, 2 and 3 only

Answer: Option 2 — 1, 2 and 3 only
Simple machines lift loads, can increase distance of effort, and can change force direction (1, 2, 3 ✓). They never violate energy conservation (4 ✗) → Option 2.
RRB Group D 2025-26 – 9 August 2026 Shift 2 · Kinetic energy

Q68. If two objects have the same velocity, which one will have more kinetic energy?

  1. (a) The one with brighter color
  2. (b) The one with larger size
  3. (c) The one with a different shape
  4. (d) The one with greater mass
Answer & solution

Answer: (d) The one with greater mass

Answer: Option 4 — The one with greater mass
KE = ½mv². For equal velocity,greater mass ⟹ more KE→ Option 4.
RRB Group D 2025-26 – 9 August 2026 Shift 3 · Potential energy

Q69. A ball is placed at the edge of a table and then at the center. The table’s height remains unchanged. How does the ball’s gravitational potential energy compare in both positions?

  1. (a) The potential energy is higher at the edge than at the center
  2. (b) The potential energy is lower at the edge than at the center
  3. (c) The potential energy is the same in both positions
  4. (d) The potential energy keeps changing as the ball moves
Answer & solution

Answer: (c) The potential energy is the same in both positions

Answer: Option 3 — The potential energy is the same in both positions
PE = mgh depends only on height. The table height is the same, so PE isunchangedwhether the ball is at the edge or centre → Option 3.
RRB Group D 2025-26 – 9 August 2026 Shift 3 · Kinetic energy

Q70. When a moving car comes to a stop, what happens to its kinetic energy?

  1. (a) It remains the same
  2. (b) It becomes double
  3. (c) It becomes negative
  4. (d) It becomes zero
Answer & solution

Answer: (d) It becomes zero

Answer: Option 4 — It becomes zero
When a moving car stops, its KE = ½mv² becomeszero(v = 0) → Option 4.
RRB Group D 2025-26 – 6 August 2026 Shift 1 · Work and its sign

Q71. If the displacement of an object doubles while the constant force remains unchanged, the area under the force–displacement graph _________.

  1. (a) becomes half of the original area
  2. (b) becomes twice the original area
  3. (c) remains unchanged
  4. (d) becomes four times the original area
Answer & solution

Answer: (b) becomes twice the original area

Answer: Option 2 — becomes twice the original area
Area under a force–displacement graph = F × d. Doubling d (F constant)doublesthe area → Option 2.
RRB Group D 2025-26 – 6 August 2026 Shift 1 · Power and its units (watt, horsepower)

Q72. A machine develops a power of 10 W. What does this imply?

  1. (a) It does 10 J of work every minute
  2. (b) It stores 10 J of energy
  3. (c) It applies a force of 10 N
  4. (d) It does 10 J of work every second
Answer & solution

Answer: (d) It does 10 J of work every second

Answer: Option 4 — It does 10 J of work every second
Power 10 W = 10 joules per second → Option 4.
RRB Group D 2025-26 – 6 August 2026 Shift 2 · Potential energy

Q73. Which of the following physical quantities affect gravitational potential energy?

  1. (a) Speed and distance
  2. (b) Temperature and colour
  3. (c) Mass and height
  4. (d) Volume and shape
Answer & solution

Answer: (c) Mass and height

Answer: Option 3 — Mass and height
Gravitational PE = mgh, so it depends onmass and height→ Option 3.
RRB Group D 2025-26 – 6 August 2026 Shift 2 · Numericals on work, energy and power

Q74. An athlete of mass 60 kg runs at 5 m/s. What is the kinetic energy gained compared to standing still?

  1. (a) 375 J
  2. (b) 1500 J
  3. (c) 750 J
  4. (d) 300 J
Answer & solution

Answer: (c) 750 J

Answer: Option 3 — 750 J
KE = ½mv² = ½ × 60 × 5² = ½ × 60 × 25 =750 J→ Option 3.
RRB Group D 2025-26 – 6 August 2026 Shift 3 · Work and its sign

Q75. A student holds a heavy school bag while waiting for the bus without moving. Which of the following statements are correct?(1) Force is applied by the student.(2) The bag is displaced.(3) Work is done on the bag.(4) No work is done in the scientific sense.

  1. (a) (2) and (3) only
  2. (b) (1) and (4) only
  3. (c) (1) and (3) only
  4. (d) (1), (2), (3)
Answer & solution

Answer: (b) (1) and (4) only

Answer: Option 2 — (1) and (4) only
Holding a bag without moving: force is applied (1 ✓) but there is no displacement, sono work is donein the scientific sense (4 ✓) → Option 2.
RRB Group D 2025-26 – 6 August 2026 Shift 3 · Simple machines and levers

Q76. Every lever consists of three essential parts that help it function. Which of the following is NOT one of these parts?

  1. (a) Load
  2. (b) Fulcrum
  3. (c) Effort
  4. (d) Axle
Answer & solution

Answer: (d) Axle

Answer: Option 4 — Axle
A lever's three parts are load, effort and fulcrum.Axleis not one of them → Option 4.
RRB Group D 2025-26 – 5 August 2026 Shift 1 · Numericals on work, energy and power

Q77. A motor develops a power of 85 W for 30 s. What is the work done by the motor?

  1. (a) 2500 J
  2. (b) 255 J
  3. (c) 2550 J
  4. (d) 250 J
Answer & solution

Answer: (c) 2550 J

Answer: Option 3 — 2550 J
Work = Power × time = 85 × 30 =2550 J→ Option 3.
RRB Group D 2025-26 – 5 August 2026 Shift 1 · Work and its sign

Q78. A football player kicks a ball forward. Later, a goalkeeper catches the ball and brings it to rest.Which of the following statements are correct?1. The player does positive work on the ball.2. The goalkeeper does negative work on the ball.3. During the kick, force and displacement are in the same direction.4. During the catch, force and displacement are in opposite directions.

  1. (a) 2 and 3 only
  2. (b) 1 and 2 only
  3. (c) 1, 2 and 4 only
  4. (d) 1, 2, 3 and 4
Answer & solution

Answer: (d) 1, 2, 3 and 4

Answer: Option 4 — 1, 2, 3 and 4
Kick: force and displacement same direction ⟹ positive work (1, 3 correct). Catch: force opposes motion (brings to rest) ⟹ negative work (2, 4 correct). All four statements are correct → Option 4.
RRB Group D 2025-26 – 5 August 2026 Shift 2 · Numericals on work, energy and power

Q79. A machine completes 3000 J of work in half a minute (30 seconds). What is the average power delivered by the machine?

  1. (a) 300 W
  2. (b) 10 W
  3. (c) 30 W
  4. (d) 100 W
Answer & solution

Answer: (d) 100 W

Answer: Option 4 — 100 W
Power = Work/time = 3000 J / 30 s =100 W→ Option 4.
*(Translated from Bengali; solved in English.)*
RRB Group D 2025-26 – 5 August 2026 Shift 2 · Numericals on work, energy and power

Q80. Machine M does 600 J of work in 20 s. Machine N does 900 J of work in 15 s. Which statement is correct?

  1. (a) Machine N develops 1.5 times the power of Machine M.
  2. (b) Machine M develops greater power.
  3. (c) Machine N develops twice the power of Machine M.
  4. (d) Both machines develop the same power.
Answer & solution

Answer: (c) Machine N develops twice the power of Machine M.

Answer: Option 3 — Machine N develops twice the power of Machine M
Power M = 600/20 = 30 W; Power N = 900/15 = 60 W =2 × 30→ Option 3.
RRB Group D 2025-26 – 5 August 2026 Shift 3 · Conservation and transformation of energy

Q81. A roller coaster car relies solely on gravitational potential energy to travel along a track. Which engineering modification will most effectively maximize the maximum speed of the car at its lowest point?

  1. (a) Introducing a secondary hill of equivalent height
  2. (b) Decreasing the structural mass of the loaded car
  3. (c) Increasing the starting elevation of the first hill
  4. (d) Replacing the underlying track with wider rails
Answer & solution

Answer: (c) Increasing the starting elevation of the first hill

Answer: Option 3 — Increasing the starting elevation of the first hill
Max speed at the bottom depends on theheight dropped(mgh → ½mv²), independent of mass. Raising the first hill increases speed most → Option 3.
RRB Group D 2025-26 – 5 August 2026 Shift 3 · Simple machines and levers

Q82. In a simple machine, the force that must be overcome is called the _____.

  1. (a) Energy
  2. (b) Load
  3. (c) Power
  4. (d) Effort
Answer & solution

Answer: (b) Load

Answer: Option 2 — Load
The resistance/force to be overcome in a machine is theload→ Option 2.
RRB Group D 2025-26 – 4 August 2026 Shift 1 · Work and its sign

Q83. Which of the following is NOT necessary for work to be done?

  1. (a) Displacement must occur
  2. (b) Energy must be stored
  3. (c) Force and displacement both must be present
  4. (d) Force must act
Answer & solution

Answer: (b) Energy must be stored

Answer: Option 2 — Energy must be stored
Work needs aforceand adisplacementin the direction of the force. Energy being *stored* is not a requirement (work can convert energy to motion/heat) → Option 2.
RRB Group D 2025-26 – 4 August 2026 Shift 1 · Numericals on work, energy and power

Q84. A water tank of mass 500 kg is placed on the roof of a building 20 m above the ground. The acceleration due to gravity is g = 10m/s². If the tank is moved to the roof of another building that is twice as high as the first building, while its mass remains unchanged, what will be its new gravitational potential energy?

  1. (a) 200,000 J
  2. (b) 400,000 J
  3. (c) 50,000 J
  4. (d) 100,000 J
Answer & solution

Answer: (a) 200,000 J

Answer: Option 1 — 200,000 J
New height = 2 × 20 = 40 m. PE = mgh = 500 × 10 × 40 =200,000 J→ Option 1.
RRB Group D 2025-26 – 4 August 2026 Shift 2 · Conservation and transformation of energy

Q85. A child swings on a swing. At which point is the child’s kinetic energy the greatest, based on the law of conservation of energy?

  1. (a) In the middle between highest and lowest points
  2. (b) At the lowest point of the swing
  3. (c) At the highest point of the swing
  4. (d) Kinetic energy is equal at all points
Answer & solution

Answer: (b) At the lowest point of the swing

Answer: Option 2 — At the lowest point of the swing
At the lowest point, PE is minimum andKE is maximum(energy conservation) → Option 2.
RRB Group D 2025-26 – 4 August 2026 Shift 2 · Simple machines and levers

Q86. A lever provides mechanical advantage greater than 1 when _______.

  1. (a) Effort arm is longer than load arm
  2. (b) Fulcrum is absent
  3. (c) Load arm is longer than effort arm
  4. (d) Both arms are equal
Answer & solution

Answer: (a) Effort arm is longer than load arm

Answer: Option 1 — Effort arm is longer than load arm
MA = effort arm/load arm > 1 when theeffort arm is longerthan the load arm → Option 1.
RRB Group D 2025-26 – 4 August 2026 Shift 3 · Kinetic energy

Q87. According to the work–energy theorem, if the net work done on an object is zero, then its kinetic energy ________.

  1. (a) Increases continuously
  2. (b) Decreases continuously
  3. (c) Remains unchanged
  4. (d) Becomes zero
Answer & solution

Answer: (c) Remains unchanged

Answer: Option 3 — Remains unchanged
Work–energy theorem: Net work = change in KE. If net work = 0, KEremains unchanged→ Option 3.
RRB Group D 2025-26 – 4 August 2026 Shift 3 · Numericals on work, energy and power

Q88. A car with a mass of 1000 kg is moving at a speed of 25 m/s. If the driver applies the brakes and brings the car to a stop, how much kinetic energy is lost during this process?

  1. (a) 312500 J
  2. (b) 625000 J
  3. (c) 12500 J
  4. (d) 25000 J
Answer & solution

Answer: (a) 312500 J

Answer: Option 1 — 312500 J
KE = ½mv² = ½ × 1000 × 25² = ½ × 1000 × 625 =312500 J(all lost when it stops) → Option 1.
RRB Group D 2025-26 – 3 August 2026 Shift 1 · Numericals on work, energy and power

Q89. The kinetic energy of a body increases from 40 J to 140 J. What is the net work done on the body?

  1. (a) 200 J
  2. (b) 150 J
  3. (c) 100 J
  4. (d) 50 J
Answer & solution

Answer: (c) 100 J

Answer: Option 3 — 100 J
Work–energy theorem:Net work done = change in kinetic energy.
W = KE_final − KE_initial = 140 − 40 =100 J→ Option 3.
RRB Group D 2025-26 – 3 August 2026 Shift 1 · Kinetic energy

Q90. Which of the following best describes kinetic energy?

  1. (a) The energy contained in chemical bonds
  2. (b) The energy an object stores in its position
  3. (c) The energy an object has due to its motion
  4. (d) The energy related to temperature changes
Answer & solution

Answer: (c) The energy an object has due to its motion

Answer: Option 3 — The energy an object has due to its motion
Concept: Kinetic energyis the energy possessed by a bodybecause of its motion, KE = ½mv². (Potential energy is due to position; chemical energy is in bonds.) → Option 3.
RRB Group D 2025-26 – 3 August 2026 Shift 2 · Kinetic energy

Q91. Which of the following is an example of kinetic energy?

  1. (a) A book on a shelf
  2. (b) A parked bicycle
  3. (c) A flying bird in the sky
  4. (d) An apple hanging from a tree
Answer & solution

Answer: (c) A flying bird in the sky

Answer: Option 3 — A flying bird in the sky
Kinetic energyis the energy ofmotion. A flying bird is moving, so it has kinetic energy → Option 3. (The others are at rest → potential energy.)
RRB Group D 2025-26 – 3 August 2026 Shift 2 · Simple machines and levers

Q92. While opening a bottle cap using a bottle opener, the resistance offered by the cap acts as the ______.

  1. (a) Machine
  2. (b) Effort
  3. (c) Energy source
  4. (d) Load
Answer & solution

Answer: (d) Load

Answer: Option 4 — Load
In a lever (bottle opener), theresistance to be overcome(the cap's grip) is theload; the force you apply is the effort → Option 4.
RRB Group D 2025-26 – 3 August 2026 Shift 3 · Work and its sign

Q93. A student applies a constant force on a box at an angle to the horizontal, and the box moves in a straight horizontal line on a rough surface. Which statement correctly describes the work done by the applied force on the box?

  1. (a) The sum of the horizontal and vertical components of the force, multiplied by the total distance traveled
  2. (b) The total applied force, including both horizontal and vertical components, multiplied by the distance moved
  3. (c) Only the vertical component of the applied force, multiplied by the distance moved vertically
  4. (d) Only the horizontal component of the applied force, multiplied by the distance moved in the same direction, gives the work done
Answer & solution

Answer: (d) Only the horizontal component of the applied force, multiplied by the distance moved in the same direction, gives the work done

Answer: Option 4 — Only the horizontal component × distance in that direction
Work = force componentalong the displacement× displacement. As the box moves horizontally, only thehorizontal componentof the force does work (the vertical component is perpendicular to motion) → Option 4.
RRB Group D 2025-26 – 3 August 2026 Shift 3 · Potential energy

Q94. An object of mass m is raised vertically through a height h near the Earth's surface. What is its gravitational potential energy?

  1. (a) mh/g
  2. (b) mg/h
  3. (c) hg/m
  4. (d) mgh
Answer & solution

Answer: (d) mgh

Answer: Option 4 — mgh
Gravitational potential energy =mgh(mass × g × height) → Option 4.
RRB NTPC UG CBT-1 2025-26 – 20 June 2026 Shift 1 · Kinetic energy

Q95. Which quantities influence the kinetic energy of a moving body?

  1. (a) Only velocity
  2. (b) Only mass
  3. (c) Its shape
  4. (d) Both mass and velocity
Answer & solution

Answer: (d) Both mass and velocity

Kinetic Energy Formula
KE = ½mv²
Where:
m = mass of the body
v = velocity of the body
From the formula, kinetic energy depends on:
• Mass (m) - directly proportional
• Velocity (v) - proportional to square of velocity
Shape does not appear in the formula.
Answer: Option 4 → Both mass and velocity
RRB NTPC UG CBT-1 2025-26 – 17 June 2026 Shift 3 · Conservation and transformation of energy

Q96. When a stretched rubber band is released, its stored potential energy is converted into which form of energy?

  1. (a) Kinetic Energy
  2. (b) Geothermal Energy
  3. (c) Hydraulic Energy
  4. (d) Chemical Energy
Answer & solution

Answer: (a) Kinetic Energy

Energy Conversion in Stretched Rubber Band
When rubber band is stretched, work is done against elastic forces.
This work is stored aselastic potential energy.
Upon release, the rubber band returns to original shape.
Stored potential energy converts tokinetic energy(motion).
Other options incorrect:
Geothermal → Earth's internal heat energy
Hydraulic → Pressure energy in fluids
Chemical → Energy in molecular bonds
Answer: Option 1 → Kinetic Energy
RRB NTPC UG CBT-1 2025-26 – 15 June 2026 Shift 3 · Power and its units (watt, horsepower)

Q97. A physicist is designing an experiment where the result depends on the product of force and velocity. Which of the following physical quantities is directly measured by this product, considering units and dimensions?

  1. (a) Power
  2. (b) Impulse
  3. (c) Energy
  4. (d) Pressure
Answer & solution

Answer: (a) Power

Given: Product of Force and Velocity
Dimensional Analysis:
Force (F) = MLT⁻²
Velocity (v) = LT⁻¹
F × v = (MLT⁻²) × (LT⁻¹) = ML²T⁻³
Check Options:
Power = Work/Time = ML²T⁻³ ✓
Impulse = F×t = MLT⁻¹ ✗
Energy = ML²T⁻² ✗
Pressure = F/A = ML⁻¹T⁻² ✗
Answer: Option 1 → Power
RRB NTPC UG CBT-1 2025-26 – 15 June 2026 Shift 3 · Commercial unit of energy (kWh)

Q98. Solar energy is globally measured in the unit of KWh. The physical quantity corresponding to the unit KWh is _____________.

  1. (a) Force
  2. (b) Electric energy
  3. (c) Current
  4. (d) Electric charge
Answer & solution

Answer: (b) Electric energy

Unit Analysis:KWh = Kilowatt-hour
KWh = Power × Time = (Watt) × (hour)
Since Power = Energy/Time
Power × Time = Energy
1 KWh = 1000 W × 3600 s = 3.6 × 10⁶ Joules
KWh is a unit ofEnergy, specifically electrical energy
Answer: Option 2 → Electric energy
RRB NTPC UG CBT-1 2025-26 – 13 June 2026 Shift 3 · Commercial unit of energy (kWh)

Q99. The commercial unit of electrical energy is kilowatt hour (kWh) and 1 kW h is equal to __________.

  1. (a) 3.6 × 10⁶ watt second
  2. (b) 3.6 × 10⁹ watt second
  3. (c) 3.6 × 10⁷ watt second
  4. (d) 3.6 × 10⁸ watt second
Answer & solution

Answer: (a) 3.6 × 10⁶ watt second

Given: 1 kWh (kilowatt hour)
Conversion:
1 kWh = 1 kilowatt × 1 hour
1 kW = 1000 watt
1 hour = 3600 seconds
Calculation:
1 kWh = 1000 watt × 3600 seconds
1 kWh = 3,600,000 watt second
1 kWh =3.6 × 10⁶ watt second
Answer: Option 1 → 3.6 × 10⁶ watt second
SSC GD 2026 – 26 May 2026 Shift 3 · Conservation and transformation of energy

Q100. At the very beginning of free fall from a certain height, how are potential energy (PE) and kinetic energy (KE) of the object related?

  1. (a) PE = 0, KE = mgh
  2. (b) PE = mgh , KE = 0
  3. (c) PE = ½mv², KE = mgh
  4. (d) Both KE and PE = 0
Answer & solution

Answer: (b) PE = mgh , KE = 0

Correct Answer: PE = mgh , KE = 0 — Option (b)
At the very beginning of free fall (the instant of release from rest at height h), PE = mgh and KE = 0. About Energy in Free Fall: At the moment of release (start of free fall): The object is at rest (velocity v = 0) at height h; Potential Energy (PE) = mgh (maximum — object is at maximum height); Kinetic Energy (KE) = ½mv² = ½m(0)² = 0 (velocity is zero); Total Mechanical Energy = PE + KE = mgh + 0 = mgh ; During the fall (at intermediate height h'): PE = mgh ' (decreasing as height decreases); KE = mg(h - h') (increasing as speed increases); Total = mgh (conserved — Law of Conservation of Energy); At the ground (just before hitting ground, h = 0): PE = mg(0) = 0 (minimum); KE = mgh (maximum — all PE converted to KE); Velocity at ground = √(2gh); Total = mgh (still conserved); Summary of energy transformation in free fall: Start: PE = max ( mgh ), KE = min (0); During fall: PE decreases, KE increases; End (ground): PE = 0, KE = max ( mgh ); This is the Law of Conservation of Mechanical Energy — total energy (PE + KE) remains constant = mgh throughout the fall (ignoring air resistance); Example: A ball of 1 kg dropped from 10 m: PE = 1 × 10 × 10 = 100 J at start, KE = 0; At 5 m height: PE = 50 J, KE = 50 J; At ground: PE = 0, KE = 100 J.
Option (a) PE = 0, KE = mgh — Incorrect: This describes the situation at the GROUND (at the END of free fall, just before impact) — NOT at the beginning; at the start of free fall, the object is at maximum height h with PE = mgh and since velocity = 0, KE = 0.
Option (c) PE = ½mv², KE = mgh — Incorrect: This is a meaningless combination — PE (Potential Energy) is mgh (not ½mv²); ½mv² is the formula for KE; at the start of free fall, PE = mgh and KE = 0 (not mgh ); this option confuses the formulas.
Option (d) Both KE and PE = 0 — Incorrect: If both KE and PE were zero at the start of free fall, that would mean the object is at zero height AND has zero velocity — this is impossible for an object at height h; at the start, PE = mgh (non-zero since h ≠ 0) and KE = 0 (since velocity = 0). The candidate selected this incorrect option.
12

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