Question

A mass is to be hung on a string to make a simple pendulum. How long should the string be if we want the pendulum to oscillate once every four seconds? (g = 10 $m{s}^{-2}$)

• A. 1.99 m
• B. 0.98 m
• C. 3.98 m
• D. 7.96 m

Answer 1

The correct option is D 7.96 m

Given $m=1kg,T=sec$

$2\pi \sqrt{\frac{l}{g}}=4$

$\sqrt{\frac{l}{g}}=\frac{2}{\pi }$

$l=\sqrt{\frac{2}{\pi }}g=7.96m$