The blades in a blender rotate at a rate of 7000 rpm. When the motor is turned off during operation, the blades slow to rest in 3.4 s. What is the angular acceleration as the blades slow down? Lets first convert rpm to rps and then multiply by 2π to get its angular velocity. 7000rpm * 60 = 420000 rps * 2π = 2638937.829 rad/s Now just simply use. Wf = Wi + AT A = Wf - Wi / T A = (0) - (2638937.829) / (3.4) A = -776158.185 rad/s^2 <-----Answer The answer is negative because its decelerating.