Work, Energy and Power

A uniform chain of length 2 m is kept on a table such that a length of 60 cm hangs freely from the edge of the table. The total mass of the chain is 4 kg. What is the work done in pulling the entire chain on the table?

• (a) 7.2 J

• (b) 3.6 J

• (c) 120 J

• (d) 1200 J

A body of mass 20 kg is initially at a height of 3 m above the ground . It is lifted to a height of 2 m from that position. Its increase in potential energy is

• (a) 100 J

• (b) 392 J

• (c) 60 J

• (d) -100 J

A body of mass 10 kg is travelling with uniform speed of 5 m/s. Its kinetic energy is

• a) 25 J

• (b) 125 J

• (c) 1250 J

• (d) 1000 J

A ball is dropped from a height of 1 m. If the coeffcient of restitution between the surface and ball is 0.6, the ball rebounds to a height of

• (a) 0.6 m

• (b) 0.4 m

• (c) 1 m

• (d) 0.36 m

A quantity of work of 1000 J is done in 2 seconds. The power utilizes is

• (a) 998 W

• (b) 1002 W

• (c) 2000 W

• (d) 500W

When the linear momentum of a particle is increased by 1% its kinetic energy increases by x%. When the kinetic energy of the particle is increased by 300%, its linear momentum increases by y%. The ratio of y to x is

• (a) 300

• (b) 150

• (c) 100

• (d) 50

A solid cylinder of length 1 m and diameter of cross section y 100 cms is first placed with its axis vertical its then slowly inclined till its axis is horizontal. The loss in its potential energy if the mass of the cylinder is 10 kg is

• (a) 5g J

• (b) 10g J

• (c) Zero

• (d) g J

A body of mass 10 kg moving at a height of 2 m, with uniform speed of 2 m/s. Its total energy is

• a) 316 J

• (b) 216 J

• (c) 116 J

• (d) 392 J

Two masses 1 g and 4 g are moving with equal kinetic energies. The ratio of the magnitudes of their linear momenta is

• (a) 4 : 1

• (b) 1 : 2

• (c) 0 : 1

• (d) 1 : 6

A body of mass 10 kg is initially at a height of 20 m above the ground. It falls to a height of 5 m above the ground. Its potential energy in the new position is

• (a) 490 J

• (b) 50 J

• (c) 100 J

• (d) 300 J