Angular acceleration of a blender

[BikeSmoth]

Homework Statement

The blades of a kitchen blender rotate counterclockwise at 2.2×10^4 rpm (revolutions per minute) at top speed. It takes the blender 2.1 seconds to reach this top speed after being turned on. What is the average angular acceleration of the blades?

Homework Equations

average angular aceleration=dw/dt

The Attempt at a Solution

after converting rpm to rotations per second I attempted 366.7rps/2.1s=174.6rad/sec

 

[Doc Al]

Convert rev/min to rad/sec, not rev/sec. (1 rev = ? radians?) And the acceleration will have units of rad/s^2.