Practice!

Sample Problem

An electric powered fan has a 9 inch diameter blade that rotates at 4000 revolutions per minute.

Find the angular speed of the sword in radians per minute.

π radians/minute

Solution

Angular speed = ω = θ/t

Each revolution is 2π radians; The fan turns (4000 revolutions/min)(2π rad/revolution)

=8000π rad per minute

Angular speed = ω = θ/t=8000π/1 minute