Question

A building is being knocked down with a wrecking ball, which is a big metal sphere that swings on a 12-m-long cable. You are (unwisely!) standing directly beneath the point from which the wrecking ball is hung when you notice that the ball has just been released and is swinging directly toward you. How much time do you have to move out of the way?

Answer 1

Because you know that gravity is in m/s^2 so, period will be measured in seconds. You know the cable is 12m long and gravity is 9.81 solve for T (period) 2π12sqrt(9.81)=6.94922

Answer 2

Answer:

Time to move out of the way = 1.74 s

Explanation:

This case is similar to simple pendulum. The period of simple pendulum is given by $2\pi \sqrt{\frac{l}{g} }$.

 Period of wrecking ball $=2\pi \sqrt{\frac{l}{g}}=2\pi \sqrt{\frac{12}{9.81}}=6.95s$

 Time to move out of the way is one fourth of period = 6.95/4 = 1.74 seconds.

 Time to move out of the way = 1.74 s