Question

A pendulum 18 cm in length swings 72 degrees from right to left. What is the

difference between the highest and lowest point of the pendulum? Round
your answer to the hundredths place.

Answer 1

3.44 cm

Explanation:

When the pendulum is at its lowest point, the vertical length of the pendulum is L.

When the pendulum is at its highest point, the vertical length of the pendulum is L cos θ.

So the height difference of the pendulum between its lowest and highest points is h = L − L cos θ.

The pendulum swings 72° from right to left, or 36° from the vertical.

The length of the pendulum is 18 cm.

So the height is:

h = L − L cos θ

h = 18 − 18 cos 36°

h = 3.44