Question

A child swinging on a swing in a sitting position, stands up, then the time period of the swing will:

• A. increase
• B. decrease
• C. remain the same
• D. increase if the child is long and decrease if the child is short

Answer 1

Answer: (B)

decrease

Answer 2

The time period of swing is given by $T =2 \pi \sqrt{\frac{l}{g}}$ $\Rightarrow T \propto \sqrt{l}$ where $l$ is the length of string. When the child stands up while swinging on a swing, the centre of gravity of the child shifts upwards and so, the length of the swing decreases. On account of this, time period of the swing will also decrease.