What is the ball’s speed at the lowest point of its trajectory?

A pendulum is made by tying a 530 g ball to a 52.0 cm-long string. The pendulum is pulled 21.0-degree to one side, then released.

Using trig, first calculate the ball’s vertical displacement at its highest point, i.e. when the string is at a 21 degree angle to the vertical. You will find that it is 104*Sin^2(10.5) = 3.4538 cm. above its lowest point.

Now calculate the speed of the ball after falling this height under a gravitational acceleration of 981 cm/sec^2 using v = (2ah)^0.5

The answer is 82.32 cm./sec

What is the ball’s speed at the lowest point of its trajectory?