A closed bottle contains some liquid. The bottle is shaken vigorously for 5 minutes. It is found that the temperature of the liquid is increased. Is heat transferred to the liquid? Is work done on the liquid? Neglect expansion on heating.
Work is done when there is displacement in the body.
Work done = force ×displacement
As the bottle is shaken vigorously, that means the bottle is displaced from its position. And this displacement is due to external force. Therefore, work is done on the bottle. Due to this work, the temperature of the liquid increases. No external heat is supplied to the bottle and liquid.