Question

A pendulum is suspended by a string of length $250cm$. The mass of the bob of the pendulum is $200g$. The bob is pulled aside until the string is at $60^{\circ }$ with vertical as shown in the figure. After releasing the bob. the maximum velocity attained by the bob will be _______$m{s}^{-1}$.
(if $g=10m/s^2$ )

Answer 1

Answer: 5

$V_{\max }=\sqrt{2gh}$

The speed will be highest at the lowest position.
$h=\left(\ell -\ell \cos 60^{\circ }\right)=\frac{\ell }{2}$
$V_{\max }=\sqrt{2\times g\times \frac{\ell }{2}}=\sqrt{10\times 2.5}=5m/s$