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NEET Physics: work-energy theorem Practice Questions

14 free multiple-choice questions on work-energy theorem (Work, Energy, and Power) for NEET Physics, each with the correct answer and a step-by-step explanation. Attempt a question, then reveal the solution to check your reasoning.

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  1. Q1. The gravitational force acting on a particle causes a change in its potential energy. If the particle is moving such that its kinetic energy increases, what must happen to its potential energy?

    • APotential energy becomes zero.
    • BPotential energy increases.
    • CPotential energy remains constant.
    • DPotential energy decreases.
    Show answer & explanation

    Correct answer: D — Potential energy decreases.

    According to the principle of conservation of mechanical energy (E = K + U), if kinetic energy increases, the potential energy must decrease, assuming the change is due to movement under gravity.

  2. Q2. When an object moves from point A to point B, the change in its kinetic energy is determined by:

    • AThe magnitude of the momentum change
    • BThe net force applied
    • CThe change in potential energy only
    • DThe net work done on the object
    Show answer & explanation

    Correct answer: D — The net work done on the object

    The Work-Energy Theorem states that the change in kinetic energy (ΔK) is equal to the net work done (Wₙₑₜ) on the object.

  3. Q3. A body is moving with a constant speed in a region where there is no net force acting on it. If the body continues to move, what is the net work done on it?

    • APositive work is done.
    • BZero work is done.
    • CWork done depends on the distance moved.
    • DNegative work is done.
    Show answer & explanation

    Correct answer: B — Zero work is done.

    Work done is calculated as W = F · d cos θ. Since there is no net force (F=0), the net work done is zero, regardless of the distance moved.

  4. Q4. A body moves from rest and achieves a final velocity of 10 m/s after being acted upon by a net force. If the net work done on the body is 50 J, what is the final kinetic energy of the body?

    • A50 J
    • B100 J
    • C125 J
    • D25 J
    Show answer & explanation

    Correct answer: B — 100 J

    According to the Work-Energy Theorem, the net work done equals the change in kinetic energy. Since the initial velocity is zero, the final kinetic energy is equal to the net work done, which is 50 J.

  5. Q5. If the kinetic energy of a body is doubled, assuming no external work is done, what happens to the net work done on the body?

    • AThe net work done is doubled
    • BThe net work done is halved
    • CThe net work done remains zero
    • DThe net work done is quadrupled
    Show answer & explanation

    Correct answer: A — The net work done is doubled

    Since W = ΔK, if K is doubled, ΔK is doubled. Therefore, the net work done must also be doubled.

  6. Q6. An object is moving along a straight path. If the net work done on the object is zero, what can be concluded about its kinetic energy?

    • AThe kinetic energy must be zero.
    • BThe kinetic energy remains unchanged.
    • CThe object must be moving with constant velocity.
    • DThe object must be at rest.
    Show answer & explanation

    Correct answer: B — The kinetic energy remains unchanged.

    Since Wₙₑₜ = ΔK, if the net work done is zero, the change in kinetic energy is zero, meaning the kinetic energy remains the same.

  7. Q7. A constant force acting on an object causes a change in its kinetic energy. According to the Work-Energy Theorem, this change in kinetic energy is equal to:

    • AThe work done by the net force
    • BThe work done by friction
    • CThe change in momentum
    • DThe potential energy gained
    Show answer & explanation

    Correct answer: A — The work done by the net force

    The Work-Energy Theorem states that the net work done on an object equals the change in its kinetic energy (Wₙₑₜ = ΔK).

  8. Q8. A constant force acts on an object, causing it to move a certain distance. If the object's kinetic energy increases by 100 Joules, what is the work done by that force?

    • A0 J
    • B-100 J
    • CUndeterminable
    • D100 J
    Show answer & explanation

    Correct answer: D — 100 J

    By the Work-Energy Theorem, the work done equals the change in kinetic energy. Since ΔK = +100 J, the work done is +100 J.

  9. Q9. If the work done in accelerating a particle is positive, what must be true about the change in its kinetic energy?

    • AKinetic energy is zero
    • BKinetic energy increases
    • CKinetic energy decreases
    • DKinetic energy remains constant
    Show answer & explanation

    Correct answer: B — Kinetic energy increases

    Work done is directly related to the change in kinetic energy. If work is positive, the kinetic energy must increase.

  10. Q10. Work is the product of the force applied in the direction of displacement and the magnitude of the displacement. If a force of 20 N is applied horizontally over a distance of 5 m in the same direction, what is the work done?

    • A10 J
    • B4 J
    • C100 J
    • D25 J
    Show answer & explanation

    Correct answer: C — 100 J

    Work done (W) is calculated as Force (F) times displacement (d). W = F × d = 20 N × 5 m = 100 J.

  11. Q11. If the total work done on a system is positive, what must happen to the kinetic energy of the system?

    • AIt depends on the mass of the system.
    • BIt must remain unchanged.
    • CIt must decrease.
    • DIt must increase.
    Show answer & explanation

    Correct answer: D — It must increase.

    Work done equals the change in kinetic energy (W = ΔK). If work is positive, the kinetic energy of the system must increase.

  12. Q12. The work-energy theorem states that the net work done on an object is equal to the change in its kinetic energy. If the change in kinetic energy is negative, what does it imply about the net work done on the object?

    • AThe net work done is positive.
    • BThe net work done is equal to the change in potential energy.
    • CThe net work done is negative.
    • DThe net work done is zero.
    Show answer & explanation

    Correct answer: C — The net work done is negative.

    According to the theorem, Wₙₑₜ = ΔK. If ΔK is negative, it means the kinetic energy decreased, thus the net work done on the object is negative.

  13. Q13. A body starts from rest and moves under the action of a net force. Which of the following statements is correct regarding the work done?

    • AWork done is positive.
    • BWork done is zero.
    • CWork done is negative.
    • DWork done depends only on the change in potential energy.
    Show answer & explanation

    Correct answer: A — Work done is positive.

    Since the body accelerates (changes its state of motion), the net force does positive work on the body, resulting in an increase in kinetic energy.

  14. Q14. A book is pushed across a rough floor with a constant force. If the book's kinetic energy increases, what is the role of the friction force acting on the book?

    • AFriction does positive work
    • BFriction is irrelevant to kinetic energy change
    • CFriction does negative work
    • DFriction does zero work
    Show answer & explanation

    Correct answer: C — Friction does negative work

    In this scenario, friction is a non-conservative force doing negative work, converting some of the applied work into heat, thus reducing the increase in kinetic energy.

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