Question

Find the length of a simple pendulum such that its time period is $2s$.

• A. $99.4cm$
• B. $89.4cm$
• C. $79.4cm$
• D. $109.4cm$

Answer 1

The correct option is A $99.4cm$

$T=2\pi \sqrt{\frac{L}{g}}\Rightarrow T^2=4{\pi }^2\times \frac{L}{g}$

$T^2=4{\pi }^2\frac{L}{g}$
$\Rightarrow 2^2=4\times 3.14\times 3.14\times \frac{L}{9.8}$
$\Rightarrow L=\frac{4\times 9.8}{4\times 3.14\times 3.14}m=0.994m=99.4cm$