Work, Energy, Power and Collisions — Practice

Question 1

A force of 10 N pulls a body through 5 m at 60° to the displacement. The work done is

Accepted Answer

A

Question 2

A satellite moves in a circular orbit. The work done by the gravitational force on it over one complete revolution is

Accepted Answer

A

Question 3

A net work of 100 J is done on a 2 kg body initially at rest. Its final speed is

Accepted Answer

A

Question 4

The gravitational potential energy of a 2 kg mass at a height of 5 m is (g = 10 m/s²)

Accepted Answer

A

Question 5

A spring stores energy E when stretched by x. If it is stretched by 2x instead, the stored energy is

Accepted Answer

A

Question 6

A body is dropped from a height of 20 m. Its speed just before hitting the ground is (g = 10 m/s², ignore air resistance)

Accepted Answer

A

Question 7

A force of 20 N moves a body at a constant 5 m/s in its own direction. The power delivered is

Accepted Answer

A

Question 8

A pump raises 100 kg of water through 10 m in 20 s. Its power output is (g = 10 m/s²)

Accepted Answer

A

Question 9

If the momentum of a body is doubled (mass unchanged), its kinetic energy becomes

Accepted Answer

A

Question 10

A ball moving at speed v collides head-on and elastically with an identical ball at rest. After the collision, the first ball

Accepted Answer

A

Question 11

A 2 kg body moving at 6 m/s strikes a stationary 4 kg body and they stick together. Their common speed is

Accepted Answer

A

Question 12

The coefficient of restitution for a perfectly elastic collision is

Accepted Answer

A

Question 13

The minimum speed at the topmost point for a body to just complete a vertical circle of radius r on a string is

Accepted Answer

A

Question 14

For the same vertical circle of radius r, the minimum speed at the lowest point to just complete the loop is

Accepted Answer

A

Question 15

A coolie carries a 20 kg load on his head and walks 50 m on level ground. The work done against gravity is

Accepted Answer

A

Practice — Work, Energy, Power and Collisions