Question 87 of 183

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 $g=10m{s}^{-2}$)

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Answer: 5

Velocity will be maximum at the bottom point when potential energy of the pendulum will be zero(considering bottom point as reference for potential energy).
$\dfrac{1}{2}m{v}^{2}=mg\left(l-l\cos 60^{\circ}\right) v=\sqrt{gl}=\sqrt{10\times 2.5}=5m{s}^{-1}$