# Swing Energy

## Homework Statement

Using the length of a swing's chain (1.8m) and using the angle the swing starts at relative to the vertical (30 deg.) devise a method to calculate the max veloc. of the swing at the bottom. Assume mass of person+swing=72 kg

Ui+Ki=Uf+Kf
K=1/2 mv^2
U=mgh
h= 1.8 cos 30
Krot= 1/2 Iw^2

## The Attempt at a Solution

(m)(9.8)(.24)=1/2 m v^2 +1/2 Iw^2
2.35= 1/2 v^2+ 1/2 r^2 (v^2/r^2)
2.35= 1/2 v^2 + 1/2 v^2
2.35=v^2
v=1.53 m/s

Do I use the rotational kinetic energy when solving the problem? It seems like I should because of the rotational motion but I'm not sure.