Question

A pendulum is suspended by a string of length 250 cm. The mass of the bob of the pendulum is 200 g. The bob is pulled aside until the string is at 60° with vertical, as shown in the figure. After releasing the bob, the maximum velocity attained by the bob will be ___ ms–1. (if g = 10 m/s2)

Fig. Oscillations

Answer 1

The correct answer is 5
$\frac{1}{2} mv² = mgl (1 - cosθ)$
$⇒ v = \sqrt{2gl (1 - cosθ)}$
$= \sqrt{2 × 10 × 2.5 × \frac{1}{2}}$
= 5 m/s