Orangutans can move by brachiation, swinging like a pendulum beneath successive handholds. If an orangutan has arms that are 0.90 m long and repeatedly swings to a 20° angle, taking one swing immediately after another, estimate how fast it is moving in m/s.

how fast it is moving in m/s? 0.65 m/s.

Explanation:

given information:

the length of the arm, L - 0.9 m

angle, θ = 20°

First we calculate the distance in horizontal motion

s = 2 L sin θ

= 2 (0.9) sin 20°

= 0.62 m

now calculate the time

t/2 = 2π√ (L/g)

t = π√ (0.9/9.8)

= 0.95 s

the speed is

v = s/t

= 0.62/0.95

= 0.65 m/s