Simple Pendulum problem?

Question

There's a simple pendulum with a string and a ball (5kg) on its end. It starts at an angle of 15 degrees from the vertical and released. (the length of the string is 1.75) How long will it take for the ball to pass through equilibrium the first time you release it?

Please help... Thanks!

Answer 1

The period of a pendulum is 2π√[L/g] = 2.656 s   That is the time it takes to swing from start to return to the start point.  Depending on where "equilibrium" is, you can determine the time.  If equilibrium is at the opposite end of the swing, the time is 1.33 sec.  If it at the bottom of the swing it is 0.664 s.