(i) Give an example of a non-contact force which is always of attractive nature.

(ii) How does the magnitude of this non-contact force on the two bodies depend on the distance of separation between them?

A boy weighing 40 kgf climbs up a stair of 30 steps each 20 cm high in 4 minute and a girl weighing 30 kgf does the same in 3 minutes. Compare :-

(i) The work done by them.

(ii) The power developed by them.

Calculate the mass of ice required to lower the temperature of 300 g of water at 40°C to water at 0°C. (Specific latent heat of ice = 336 J g^-1, Specific heat capacity of water = 4.2 J g^-1 °C^-1)

What do you understand by the following statements :

(i) The heat capacity of the body is 60 J K^-1.

(ii) The specific heat capacity of lead is 130 J kg^-1 K^-1