Merry-go-round childs speed... easy

Question

A 5.0-m-diameter merry-go-round is initially turning with a 4.5 s period.

What is the speed of a child on the rim? Answer in m/s and two significant figures

Answer 1

Circumference = pi * diameter = 16 m.

16 m / 4.5 s = 3.5 m/s