83 free MCQs on Work, Energy and Power, each with its own worked answer and explanation. Work-energy theorem, potential energy, conservation of energy, collisions.
Take the timed Work, Energy and Power chapterwise test →83 practice questions on Work, Energy and Power, sorted Easy → Hard. Try each one first, then open its answer page for the worked explanation. Want the full theory first? Read the Work, Energy and Power notes.
As a pendulum swings, total mechanical energy (KE+PE) stays constant: at the highest points A and C, all energy is potential (zero speed); at the lowest point B, all of that energy has converted into kinetic energy (maximum speed).
Q1.
The dimensional formula of energy (or work) is:
Q2.
One electron volt (1 eV) is equal to approximately:
Q3.
The area under a force versus displacement (F-x) graph represents the:
Q4.
A body moves with constant velocity along a horizontal frictionless surface. The net work done on it is:
Q5.
Work done is zero when force is applied:
Q7.
A force of 10 N moves a body 5 m in its direction. Work done is:
Q8.
Kinetic energy of a 2 kg body moving at 10 m/s is:
Q9.
When a ball is thrown up, its kinetic energy at the highest point is:
Q10.
Potential energy of a 5 kg body at height 10 m is (g=10):
Q11.
The work-energy theorem states that net work done on a body equals:
Q12.
Power is defined as:
Q13.
1 kilowatt-hour (kWh) equals:
Q14.
Which does NOT do work on a moving body in circular motion?
Q15.
If mass of a body doubles and speed remains same, its KE becomes:
Q16.
A spring stores which type of energy when compressed?
Q17.
When a ball falls from height h to ground, what happens to its mechanical energy (ignoring air resistance)?
Q18.
A machine does 1000 J of work in 10 seconds. Its power is:
Q19.
Negative work is done when force acts:
Q21.
If speed of a body doubles, its kinetic energy becomes:
Q22.
A body in free fall: as it falls, kinetic energy:
Q23.
What is the energy stored in a stretched rubber band called?
Q24.
In an elastic collision, which quantity is conserved?
Q25.
A constant force of 50 N moves a body at a steady velocity of 4 m/s along the direction of the force. The power delivered is:
Q26.
The speed of a 2 kg body increases from 3 m/s to 5 m/s. The work done on it is:
Q27.
Two bodies of masses 1 kg and 4 kg have equal kinetic energies. The ratio of their momenta (lighter : heavier) is:
Q28.
A body of mass 4 kg has a linear momentum of 20 kg·m/s. Its kinetic energy is:
Q29.
A spring of force constant 100 N/m is stretched from 0.1 m to 0.2 m beyond its natural length. The work done is:
Q30.
A 1 kg ball falls from 20 m height. Speed just before hitting ground (g=10):
Q31.
Work done by friction is always:
Q32.
A spring of k=200 N/m is stretched by 0.1 m. Elastic PE stored is:
Q33.
A 60 kg man climbs 15 m stairs in 1 minute. Power developed is (g=10):
Q34.
A car of mass 1000 kg is driven at constant speed 20 m/s by engine power 40 kW. Friction force is:
Q35.
Ball of mass 2 kg moving at 10 m/s hits wall and rebounds at 8 m/s. Energy lost:
Q36.
A force F = 3x N acts on a particle moving from x=0 to x=4 m. Work done is:
Q37.
An engine pumps water at 60 kg/min to a height of 50 m. Minimum power needed (g=10):
Q38.
In an inelastic collision, total kinetic energy:
Q39.
A 5 kg body is raised 2 m and then moved 3 m horizontally. Work done against gravity is (g=10):
Q40.
A 2 kg ball is dropped from 5 m. Its KE just before hitting the ground is:
Q41.
Work done by gravity on a satellite in circular orbit is:
Q42.
A body moves under a conservative force. Which statement is always true?
Q43.
Power dissipated by a 4 ohm resistor carrying 3 A current:
Q44.
Coefficient of restitution (e) for perfectly elastic collision is:
Q45.
A car of mass 500 kg accelerates from 0 to 30 m/s. Work done by engine (ignoring friction):
Q46.
On a frictionless slope of height h, a ball slides from rest. Speed at bottom depends on:
Q47.
A 200 W bulb is used for 5 hours. Energy consumed in kWh:
Q48.
Which force is non-conservative?
Q49.
A body has KE = 64 J and speed = 4 m/s. Its mass is:
Q50.
A pump raises 600 kg of water per minute from a well 15 m deep and ejects it at 10 m/s (g = 10 m/s<sup>2</sup>). The power delivered by the pump is:
Q51.
A body falls freely from rest from a height H. At what height above the ground is its kinetic energy three times its potential energy?
Q52.
A 10 g bullet moving at 200 m/s embeds in a 990 g block that can then swing freely as a pendulum. The maximum height the block rises is (g = 10 m/s<sup>2</sup>):
Q53.
A 2 kg ball moving at 4 m/s collides head-on with a 3 kg ball at rest. If the coefficient of restitution is 0.5, the speed of the 3 kg ball after collision is:
Q54.
A 1000 kg car runs under a constant engine power of 50 kW. When its speed is 10 m/s and the resistive force is 1000 N, its acceleration is:
Q55.
A uniform chain of mass 6 kg and length 3 m lies on a table with one-third of its length hanging over the edge. The work needed to pull the hanging part back onto the table is (g = 10 m/s<sup>2</sup>):
Q56.
A particle of mass 0.5 kg moves in x-direction with F = (3x<sup>2</sup> + 2) N. Work from x=0 to x=3 m:
Q57.
A ball is projected horizontally at 20 m/s from 20 m height. KE when it hits ground (g=10, m=1 kg):
Q58.
A 1 kg block compresses spring (k=100 N/m) by 0.2 m. Maximum speed of block when released (spring on frictionless surface):
Q59.
Two bodies m and 2m moving toward each other at 3v and v elastically. Speed of heavier body after collision:
Q60.
A pendulum of length 1 m swings to maximum angle 60 deg from vertical. Speed at bottom (g=10):
Q61.
A 1000 kg car engine has efficiency 30% and consumes fuel at 10 kW. Maximum speed on level road with friction 500 N:
Q62.
A body of mass m slides down a rough incline of height h and angle theta. mu_k between body and surface. Speed at bottom:
Q63.
Power of a pump that raises 10 kg of water per second to a height of 20 m and gives it velocity 5 m/s (g=10):
Q64.
A spring of k=500 N/m has its PE equal to KE when displacement from equilibrium is (max amplitude = A):
Q65.
A block of 2 kg falls onto a spring (k=1000 N/m) from height 2 m above spring. Maximum compression (g=10):
Q66.
At what height will potential energy be 60% of total mechanical energy for a projectile at angle theta with speed u?
Q67.
A ball dropped from height H on elastic floor bounces back to height h. Coefficient of restitution is:
Q68.
A 5 kg body moving at 4 m/s collides and sticks to a 3 kg body moving at 2 m/s in same direction. Final KE:
Q69.
Efficiency of a heat engine is 40%. If it takes in 5000 J of heat, work output is:
Q70.
A 2 kg block slides 3 m on a rough floor (mu=0.2) and compresses a spring 0.5 m. Initial KE of block (g=10):
Q71.
A particle moves from (0,0) to (3,4) m. Force on it is F=(2x + 3) i N (only x-component). Work done:
Q72.
A body of mass m is raised through height h on a slope of angle theta. If mu is the coefficient of friction, total work done against gravity and friction is:
Q73.
A force F acts on a particle such that PE = (3x<sup>2</sup> + 2x) J. Force at x=2 m:
Q74.
Two identical balls collide elastically head-on. Ball 1 is at rest. After collision:
Q75.
A particle of mass m is attached to spring (k). At position x from equilibrium, the total energy equals KE when:
Q76.
A force F = (2x + 3) N acts on a body along the x-axis. The work done as the body moves from x = 0 to x = 2 m is:
Q77.
A pump lifts 100 kg of water per second through a height of 10 m (g = 10 m/s²). The power of the pump is:
Q78.
A 2 kg block moving at 6 m/s collides head-on and sticks to a 4 kg block at rest. The kinetic energy lost in the collision is:
Q79.
A 1 kg block on a rough surface (μ = 0.2, g = 10 m/s²) is given an initial speed of 10 m/s. The distance it travels before stopping is:
Q80.
In a perfectly elastic head-on collision between two equal masses, one initially at rest, the fraction of kinetic energy transferred to the stationary mass is:
Q81.
A car of mass 500 kg accelerates from rest to 20 m/s in 10 s on a level road. The average power delivered is:
Q82.
A spring of constant 200 N/m is compressed by 10 cm. The elastic potential energy stored is:
Q83.
A 2 kg body is dropped from a height of 5 m (g = 10 m/s²). Its kinetic energy just before striking the ground is:
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