Angular Velocity — Merry-Go-Round (Worked Example)
Problem
A child on a merry-go-round's edge (radius 2.0 m) moves at 3.0 m/s. What is the angular velocity of the ride?
Given
v = 3.0 m/s
r = 2.0 m
Find
Angular velocity ω.
Principle
Linear and angular speed are linked by v = ωr — every point on a rigid rotator shares one ω.
Formula
ω = v/r
Solution
Rearrange:
Substitute:
Divide:
1.5 rad/s
Unit check
(m/s) ÷ m = 1/s = rad/s — correct.
What this means physically
1.5 rad/s is about one revolution every 4.2 s — a brisk but comfortable ride. A child halfway in (r = 1 m) moves at only 1.5 m/s with the same ω.
Common mistake
Thinking ω changes with radius. On a rigid merry-go-round ω is identical everywhere — it is the linear speed v = ωr that grows outward.