Well, if the radius is 10, then the circumference is [tex]\frac{2*10*22}7=\frac{440}7[/tex]
What's the unit? Either way, 22 rev. per minute means each minute you go by [tex]22*\frac{440}7=\frac{9680}7[/tex] units per second. Now you got the linear speed, just find out the time by dividing the distance by the speed!
So, what's the unit for the radius?
