A man whose mass is 50 kg climbs up 30 steps of a stair in 30 s. If each step is 20 cm high, calculate the power used in climbing stairs.

A person carrying 10 bricks each of mass 2.5 kg. on his head moves to a height 20 metres in 50 seconds. Calculate the power spent in carrying bricks of the person.

An iron smaple having mass 8.4 kg is repeatedly taken over cycles of magnetisation and demagnetisation at a frequency of 50Hz. It is found that energy of 3.2 J is dissipated as heat in the sample in 30 minutes. If the denstiy of iron is 7200 kg m^-3 , calculate the value of energy dissipated per unit volume per cycle in the iron sample.

Four sphere each of mass 10 kg and of radius 20 cm are placed at the four cornes of a square of side 100 cm. Calculate the moment of inertia of the system about an axis coinciding with side of the square (given moment of inertia of sphere = 2/5 MR^2 )

Four sphere each of mass 10 kg and of radius 20 cm are placed at the four cornes of a square of side 100 cm. Calculate the moment of inertia of the system about an axis coinciding with diagonal of the square. (given moment of inertia of sphere = 2/5 MR^2 )

Two children A and B each weigh 20 kg climb a rope up a height of 10 m. The child A takes 10 s, and child B take 20s, to climb. Out of these two children, who has more power? Compare their powers.

Two children A and B each weigh 20 kg climb a rope up a height of 10 m. The child A takes 10 s, and child B take 20s, to climb. State whether the work performed by both the children is equal or different.

A monkey of mass 40kg climbs on a rope (Fig. 5.20) which can stand a maximum tension of 600 N. in which of the following cases will the rope break: the monkey:- climbs up with a uniform speed of 5 m s^-1