A simple pendulum consists of a hollow sphere filled with mercury. As the mercury begins to leak out slowly through a small hole at the bottom, the time period of the pendulum will (a) decrease continuously until the sphere is empty. (b) first increase and then decrease to the original value. (c) remain constant throughout. (d) increase continuously until the sphere is empty.

Answer: (b). Effective length l is up to the centre of mass of the bob, and T ∝ √(l). As mercury leaks, the centre of mass drops first ( T increases), then rises back to the sphere's centre when empty ( T returns to original). So the answer is (b) first increase and then decrease to the original value.

A simple pendulum consists of a hollow sphere filled with mercury. As… | MHT CET 2026 (19 May, Shift 2)

Q2MHT CET 2026 · 19 MAY · SHIFT 2Easy

Simple Pendulum

A simple pendulum consists of a hollow sphere filled with mercury. As the mercury begins to leak out slowly through a small hole at the bottom, the time period of the pendulum will

Show answer and solution

Answer: (b)

Effective length $l$ is up to the centre of mass of the bob, and $T \propto \sqrt{l}$ .
As mercury leaks, the centre of mass drops first ( $T$ increases), then rises back to the sphere's centre when empty ( $T$ returns to original).
So the answer is (b) first increase and then decrease to the original value.

Report a mistake

Simple Pendulum question from MHT CET 2026 (19 May, Shift 2)

More questions on Simple Pendulum