The average work done by a human heart while it beats once is 0.5 J. Calculate the power used by heart if it beats 72 times in a minute.

In an elastic collision of two billiard balls, which of the following quantities remain conserved during the short time of collision of the balls (i.e., when they are in contact).

(a) Kinetic energy.

(b) Total linear momentum? Give reason for your answer in each case.

Calculate the power of a crane in watts, which lifts a mass of 100 kg to a height of 10 m in 20s.

Give example of a situation in which an applied force does not result in a change in kinetic energy.

Two bodies of unequal mass are moving in the same direction with equal kinetic energy. The two bodies are brought to rest by applying retarding force of same magnitude. How would the distance moved by them before coming to rest compare?