Question

A coin completes 18 spins in 12 seconds. The centripetal acceleration of the edge of the coin is 2.2 m/s^2. The radius of the coin is ____ m.
A. 0.025
B. 0.037
C. 2.1
D. 8.0
HELP!

Answer 1

Ac = V^2 / r
Ac = 2.2
V = (18/12) * 2πr

2.2 = 9(π^2)(r^2) / r
= 9(π^2)r
Therefore,
r = 2.2 / 9(π^2) = 0.02476740044...
So roughly 0.025. Answer A.