1Write the definition of work and its unit.
2If a person pushes hard against the wall of a house, is work done or not? Give the reason.
3If a man is walking with a heavy load on his head, is he doing work or not? Explain.
4Write the definition of power and its unit.
5Two people do equal work. In what condition is their power equal, and in what condition is it different?
6A crane takes 20 s to lift a 1500 kg jeep to a height of 120 m. Find the work done and the power.
7A man carries a 50 kg sack of rice to the roof of a bus 3 m high, then drags it 4 m against 450 N of friction. Find the work done against gravity and against friction.
8Explain the difference between work done against friction and work done against gravity, with examples.
9Why is power described as a rate, and what else in this unit is a rate?
10A student climbs the same staircase twice, once slowly and once quickly. What changes and what does not?