Question

The length of a simple pendulum is $1m$. The bob is given a velocity $7m{s}^{-1}$ in horizontal direction from mean position. During upward motion of bob, if the string breaks when it is horizontal, then the maximum vertical height of ascent of bob from rest position is:

• A. $2.5m$
• B. $2m$
• C. $3m$
• D. $3.5m$

Answer 1

The correct option is A $2.5m$

WET between A and B.

$\left(mg\right)1=\frac{1}{2}m\left(7^2\right)-\frac{m}{2}{v}^2$

$10=\frac{49}{2}-\frac{v^2}{2}$

$v=\sqrt{29}$

Maximum vertical ht. from pt. B.
$H=\frac{v^2}{2g}$$=\frac{29}{20}=1.45m$

Total ht. from mean position $=1+H$ $=2.45m$