A child swinging on a swing in sitting position, stands up

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

  1. Remains same
  2. Decreases
  3. Increases
  4. Increase if the child is tall, decrease if the child is short

Answer

As the child stand up the effective length of pendulum decreases due the reason that center of gravity rises up.

According to T = 2π√(l/g)

The time period decreases.

The correct option is B.