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JEE • PHYSICS • WORK-ENERGY-POWER

Work-energy-power practice · Hard

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Practice format and chapter quiz

These sets use single-correct-answer MCQs. They do not cover every JEE Main or JEE Advanced question format and are not full-length mock papers.

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1 Hard

1 of 9

Application +4 | -1

A mason is supplied with bricks by his assistant who is

3 {~m}

below him, the assistant is tossing the brick vertically up. The speed of the brick, when it reaches the mason is

2 {~ms}^{-1}

. What percentage of energy used up by the servant serves no useful purpose?

View answer and explanation

Correct option: A

5.6

Option B (10 N) is correct because the average force is calculated using the impulse-momentum theorem.

2 Hard

2 of 9

Application +4 | -1

The potential energy

U=3 a x^3-2 b x^2

. The force constant is represented by

View answer and explanation

Correct option: C

4 b

Option C (

4 b

) is correct because the force constant is the second derivative of the potential energy with respect to x, evaluated at equilibrium.

3 Hard

3 of 9

Application +4 | -1

A bullet of mass 25 g moving with velocity of 400 m/s enters into a wooden block and comes out of it with a velocity of 100 m/s. Find the work done by the bullet while passing through the wooden block.

View answer and explanation

Correct option: B

1875 J

Option B (1875 J) is correct because the work done is equal to the change in kinetic energy of the bullet.

4 Hard

4 of 9

Application +4 | -1

A motor is used to deliver water at a certain rate from a given pipe. To obtain 3 times water from same pipe in same time, by what factor should power of the motor be increased.

View answer and explanation

Correct option: D

27 times

Option D (27 times) is correct because the power is proportional to the cube of the velocity required to deliver the water at a certain rate.

5 Hard

5 of 9

Understanding +4 | -1

Assertion: Water at the foot of the water fall is always at different temperature from that at the top.
Reason: The potential energy of water at the top is converted into heat energy during falling.

View answer and explanation

Correct option: A

If both Assertion and Reason are true and Reason is the correct explanation of Assertion

Option A (If both Assertion and Reason are true and Reason is the correct explanation of Assertion) is correct because the potential energy of the water is converted into kinetic energy and then thermal energy, increasing the temperature.

6 Hard

6 of 9

Application +4 | -1

If potential energy is

U=3 x^2-2 x,

then force will be:

View answer and explanation

Correct option: A

\vec{{F}}=(-6 x+2) \hat{{i}}

Option A (

\vec{{F}}=(-6 x+2) \hat{{i}}

) is correct because force is the negative gradient of the potential energy function.

7 Hard

7 of 9

Understanding +4 | -1

Assertion: There is no loss in energy in elastic collision
Reason: Linear momentum is conserved in elastic collision

View answer and explanation

Correct option: B

If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion

Option B is correct because both energy and momentum are conserved in elastic collisions, but conservation of momentum doesn't explain conservation of energy.

8 Hard

8 of 9

Application +4 | -1

A sphere

P

of mass

m

and velocity

\overrightarrow{v_i}

undergoes an oblique and perfectly elastic collision with an identical sphere

Q

initially at rest. The angle

\theta

between the velocities of the spheres after the collision shall be

View answer and explanation

Correct option: C

90^{\circ}

Option C (

90^{\circ}

) is correct because in a perfectly elastic collision between identical masses, with one initially at rest, the angle between their velocities after the collision is 90 degrees.

9 Hard

9 of 9

Analyzing +4 | -1

Assertion: It is not possible to accelerate if travelling at a constant speed.

Reason: It is not possible to round a curve with zero acceleration.

View answer and explanation

Correct option: D

If the assertion is false and reason true

Option D (If the assertion is false and reason true) is correct because an object can accelerate while maintaining constant speed (e.g., circular motion), and rounding a curve requires acceleration.

Revision notes and key takeaways

Review WORK-ENERGY-POWER in your textbook or class notes, then use this set to check your understanding.

Key Takeaways

✓ This set contains 9 single-correct-answer MCQs on WORK-ENERGY-POWER.
✓ Try each question before opening its answer. Read the explanation where one is available.
✓ Sign in to save submitted answers. Revisit incorrect answers alongside your textbook or class notes.

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