Question

A freely falling body takes 2 seconds to reach the ground on a planet, when it is dropped from a height of 8 m. If the period of a simple pendulum is $\pi$ seconds on the planet, the length of the pendulum is

• A. $1m$
• B. $2m$
• C. $1.5m$
• D. $3m$

Answer 1

The correct option is A $1m$

$h=\frac{1}{2}a{t}^2$

$8=\frac{1}{2}a(2{)}^2$

$a=4m/s^2$
$T=2\pi \sqrt{\frac{l}{a}}$
$T=\pi$

Hence $l=1$m