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NEET Work, Energy and Power: 5 practice MCQs with answers

By the PrepMatic team · Updated 9 Oct 2026 · 3 min read

Work, Energy and Power is a short chapter with wide use: the work-energy theorem and conservation of energy turn many hard dynamics problems into one-line equations. The five MCQs below cover work by a constant force, kinetic energy and momentum, power, spring energy and an elastic collision, all at NCERT Class 11 level.

What this chapter covers in the NEET syllabus

The NMC unit is Work, Energy and Power, matching the Class 11 NCERT chapter of the same name. The topics are:

• Work done by a constant force and a variable force, and work as a scalar (dot) product.
• Kinetic energy and the work-energy theorem.
• Potential energy, the potential energy of a spring, and conservative forces.
• Conservation of mechanical energy.
• Power, average and instantaneous, and the unit watt.
• Collisions in one dimension: elastic and inelastic.

Five practice MCQs on Work, Energy and Power

Question 1

A force of 10 N acts on a body at an angle of 60° to its displacement of 4 m. The work done by the force is:

• A. 40 J
• B. 34.6 J
• C. 20 J
• D. 5 J

Question 2

The kinetic energy of a body is increased by 300%. Its linear momentum then increases by:

• A. 300%
• B. 200%
• C. 150%
• D. 100%

Question 3

A pump lifts 100 kg of water through a height of 6 m every minute. Taking g = 10 m/s², the power it delivers is:

• A. 100 W
• B. 600 W
• C. 36 W
• D. 6000 W

Question 4

A spring of force constant 200 N/m is compressed by 0.1 m. The elastic potential energy stored in it is:

• A. 20 J
• B. 2 J
• C. 0.1 J
• D. 1 J

Question 5

A body of mass m moving at speed v collides head-on and elastically with an identical body at rest. After the collision, the second body moves with speed:

• A. v/2
• B. 2v
• C. v
• D. zero

Answers and explanations

1. C. W = F d cos θ = 10 × 4 × cos 60° = 10 × 4 × 0.5 = 20 J. Option A forgets the cosine of the angle.
2. D. An increase of 300% means the new kinetic energy is 4 times the old one. Since momentum p = √(2mK), it is proportional to √K, so the momentum doubles. That is an increase of 100%, not 200%.
3. A. Power = work/time = mgh/t = (100 × 10 × 6)/60 = 6000/60 = 100 W. Do not forget to convert the minute to 60 seconds.
4. D. U = ½kx² = ½ × 200 × (0.1)² = ½ × 200 × 0.01 = 1 J. Squaring the compression before multiplying is where students slip.
5. C. In a one-dimensional elastic collision between equal masses, the bodies exchange velocities. The first body stops and the second moves off with speed v. Both momentum and kinetic energy are conserved.

How to prepare Work, Energy and Power

• Reach for the work-energy theorem first. When a question gives speeds at two positions and asks about a force or a distance, equate net work to the change in kinetic energy. It avoids needing the time or the acceleration.
• Watch the sign of work. Friction and the work done by gravity on a rising body are negative. Work by a force perpendicular to the displacement is zero, as with the centripetal force or the normal reaction.
• Learn the K and p relations. With p = √(2mK), questions about changes in momentum and energy become a single line of ratios, as in Question 2.
• Know the collision cases. For a perfectly inelastic collision the bodies stick together and kinetic energy is lost. For an elastic collision, both are conserved, and equal masses exchange velocities.
• Keep power formulas together. P = W/t on average, and P = F v for a force at constant velocity. For vehicles, P = F v at constant speed links the engine power to the resistive force.

A reasonable target is two sittings of 20 problems each, then a mixed set of energy questions every few days until the chapter is automatic. Chapter order and priorities for Physics are in the NEET Physics preparation guide, and the unit list is in the NEET syllabus.

Take a full Work, Energy and Power test on PrepMatic

Energy problems reward speed once the formulas are automatic. A PrepMatic topic test (about 15 questions, 30 minutes) shows your accuracy under time pressure, with negative marking applied as in NEET. The free Basic plan includes topic tests, and you will find more chapters on the practice hub.

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