Question

the period of a simple pendulum of length 80cm was found to have doubled when the length of the pendulum was increades by x. calculate x

Answer 1

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

$2T=2\pi \sqrt{\frac{l+x}{g}},$

$2\sqrt{\frac{l}{g}}= \sqrt{\frac{l+x}{g}},$

$4l=l+x,$

$x=3l,$

$x=3\cdot 80=240~cm.$