To solve this problem, we must always remember that energy is conserved. In this case, since he is falling down, he has highest potential energy at the top and zero at bottom. While his kinetic energy is zero at the top since he started from rest and highest at the bottom. We can also say that Potential Energy lost is Kinetic Energy gained thus,
- ΔPE = ΔKE ---> one is negative since PE is losing energy
- m g (h2 – h1) = 0.5 m (v2^2 – v1^2)
Where,
m = mass of tarzan (cancel that out)
g = gravitational acceleration
h2 = height at the bottom= 0
h1 = height at top = 22 m
v2 = velocity at the bottom
v1 = velocity at top = 0 (started from rest)
Therefore substituting all values:
- 9.8 (- 22) = 0.5 (v2^2)
v2 = 20.77 m / s (ANSWER)
