A body of mass 1 kg is thrown upwards with a velocity of It momentarily comes to rest after attaining a height of 18 m. How much energy is lost due to air friction?
1. 20 J
2. 30 J
3. 40 J
4. 10 J
1. | no work is done by the tangential force. |
2. | no work is done by the centripetal force. |
3. | work done by the tangential force is always positive. |
4. | work done by the centripetal force is negative. |
Two springs of spring constants k and 3k are stretched separately by the same force. The ratio of potential energy stored in them respectively, will be:
1. | 3: 1 | 2. | 9: 1 |
3. | 1: 3 | 4. | 1: 9 |
Mark the correct statement(s):
1. Internal forces cannot increase the kinetic energy of a system.
2. Internal forces may increase the kinetic energy of a system.
3. Work done by kinetic friction is always negative.
4. Both (2) & (3)
A bullet fired towards a wall reduces its kinetic energy by half after the penetration of 6 cm. The further penetration of the bullet into the wall is:
1. 2 cm
2. 1 cm
3. 6 cm
4. 3 cm
A body having an initial kinetic energy 2 J collides with an identical body at rest. The maximum loss of kinetic energy in the collision will be:
1. | 2 J | 2. | Zero |
3. | 1 J | 4. | 1.5 J |
What is the work done by gravity on block A in 2 seconds after the blocks are released? (Pulley is light)
1. 240 J
2. 200 J
3. 120 J
4. 24 J
A weight 'mg' is suspended from a spring. The energy stored in the spring is U. The elongation in the spring is:
1.
2.
3.
4.
The energy required to accelerate a car from rest to 30 m/s is E. The energy required to accelerate the car from 30 m/s to 60 m/s will be:
1. | E | 2. | 2E |
3. | 3E | 4. | 4E |