Question

The bob of a simple pendulum is a spherical hollow ball filled with water. A plugged hole near the bottom of the oscillating bob gets suddenly unplugged. During observation, till water is coming out, the time period of oscillation would

• A. First increase and then decrease to the original value
• B. First decrease and then increase to the original value
• C. Remain unchanged
• D. Increase towards a saturation value

Answer 1

Answer: (A)

and $T_1>T_2$

The given system is like a simple pendulum whose effective length is between the point of suspension and the center of gravity of the hanging body.
When water slowly flows out, the sphere, the centre of gravity. of system is changing as shown in the figures.
Hence, time period first increases and then decreases to the original value.