A 336 g ball is tied to a string It is pulled to an angle of

A 336 g ball is tied to a string. It is pulled to an angle of 5.6 and released to swing as a pendulum. A student with a stopwatch finds that 25 oscillations take 13 s . Part A How long is the string?

With work please!!

Solution

The formula for the period of the swing is T=2*pi*sqrt(length/gravity).
since 25 oscillations take 13 seconds, T=13/25=.52

solving the equation for length gives length = (T/(2*pi))^2*gravity
length = (.52/(2*3.1415927))^2*9.8

The answer is 0.0670m

The mass of the ball doesn\'t matter, and the original angle must be small to use this formula.