When a body moves in a circular path in a horizontal plane, the work done is :

1. Positive
2. Negative
3. Zero
4. Maximum

When a ball m is thrown upwards to a height h, the work done by the force of gravity is:

1. mgh
2. -mgh
3. mg
4. mgh²

A coolie A takes 1 minute to lift a load to the roof of a bus whereas coolie B take 2 minutes to lift the same load to the roof of the same bus. The work done by B is:

1. equal to work done by A
2. greater than work done by A
3. less than work done by A
4. none of the above.

One horse power is equal to :

1. 1000 W
2. 500 W
3. 764 W
4. 746 W