A hollow sphere is filled with water . It is hung by a long thread . As the water flows out of a hole at the bottom , the period of oscillation will

Options

A. first increases and then decrease
B. first decrease and then increase
C. increases continuously
D. decreases continuously

Answer

A

Explanation

As the water flows out of the sphere , the time period first increases and then decreases. Initially when the sphere is completely filled with water its centre of gravity (C.G) lies at its centre. As water flows out, the C.G begins to shift below the centre of the sphere. the effective length of pendulum increases and hence time peirod increases.
When the sphere becomes more than half empty, its C.G beings to rise up. The effective lenght of the pendulum decreases and T decreases.