A circular saw blade completes 1250 revolutions in 39 s while coasting to a stop after being turned off. Assume constant deceleration.

(a) What is the angular deceleration?

(b) What is the initial angular speed?


Thanks for your help

Wo = initial angular velocity
W = final angular velocity (=0 in your case)
a = angular accellaration
@ = angular displacement.

Use W = Wo + at , put W =0 and t= 39s and get Wo = -39a.

Use @ = Wot + (1/2)at^2, put Wo = -39a, t= 39s, @(angular displacement) = 2*3.14*1250 and find a, the angular accellaration.

Come back to first equation again and find Wo.
Can you do now ?