These Objective Questions on Work, Energy and Power (Class XI, Physics) will help you in preparing for different examinations like AIEEE, AIPMT, IIT, and other +2 level competitive exams, and will also help in many government exams that ask the basics of physics.

1. When the momentum of a body increases by 200%, its KE increases by how much percent ?

  • 100
  • 200
  • 400
  • 800

2. Two bodies of masses m1 and m2 are moving with same kinetic energy. If P1 and P2 are their respective momentum, the ratio P1 P2 is equal to –

  • m1/m2
  • sqrt(m1/m2)
  • sqrt(m2/m1)
  • m2/m1

3. KE acquired by a mass m in travelling a certain distance d, starting from rest, under the action of a constant force F is ?

  • Directly proportional to m
  • Directly proportional to √m
  • Directly proportional to 1/m
  • None of these
None of these

4. A simple pendulum with the bob of mass m and length x is held in position at an angle θ1 and then angle θ2 with the vertical. When released from these positions, speeds with which it passes the lowest positions are v1 & v2 respectively. Then, v1/v2 is

  • 1-cos θ1/1-cos θ2
  • sqrt(1-cos θ1/1-cos θ2)
  • sqrt(2gx(1-cos θ1)/1-cos θ2)
  • sqrt((1-cos θ1)/2gx(1-cos θ2))
sqrt(1-cos θ1/1-cos θ2)

5. A U–238 nucleus originally at rest, decays by emitting a α-particle, say with a velocity of v m/s. The recoil velocity (in m/s) of the residual nucleus is ?

  • -4v/234
  • v/234
  • v/4
  • 4v/238

6. The total work done on a particle is equal to the change in its kinetic energy. This is applicable –

  • Always
  • Only if the conservative forces are acting on it
  • Only in inertial frames
  • Only when pseudo forces are absent

7. Potential energy is defined – 

  • Only in conservative fields
  • As the negative of work done by conservative forces
  • As the negative of work done by external forces when ΔK = 0
  • All of these
Only in conservative fields

8. A spring with spring constants ‘k’ when compressed by 1 cm, the potential energy stored is U. If it is further compressed by 3 cm, then the change in its potential energy is ?

  • 3U
  • 9U
  • 8U
  • 15U

9. Two springs have force constant K1 and K2 (K1 > K2). Each spring is extended by same force F. If their elastic potential energy are E1 and E2 then E1/E2 is ?

  • K1 / K2
  • K2 / K1
  • √(K2 / K1)
  • √(K1 / K2)
K2 / K1

10. An unloaded bus can be stopped by applying brakes on a straight road after covering a distance x. Suppose, the passenger add 50% of its weight as the load and the braking force remains unchanged, how far will the bus go after the application of the brakes ? (Velocity of bus in both cases is same)

  • Zero
  • 1.5x
  • 2x
  • 2.5x

11. Initially, mass m is held such that spring is in a relaxed condition. If mass m is suddenly released, maximum elongation in the spring will be ?

  • mg / k
  • 2mg/k
  • mg/2k
  • mg/4k

12. The power of water pump is 4 kW. If g = 10 m/s2, the amount of water it can raise in 1 minute to a height of 20 m is (1 litre = 1Kg)

  • 100 litre
  • 1000 litre
  • 1200 litre
  • 2000 litre
1200 litre

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