**Question:**

“an automobile engine slows down from 4500rpm to 1200rpm in2.5seconds..Calculate..

A) Angular Acceleration assumed constant, and

B) The total number of revolutions the engine makes in this time”

**Answer:**

Î±=(Ï‰2-Ï‰o2)/t, so first convert the rpm’s to

rad/s then you get 472.5rad/s and 126rad/s and

the acceleration is -138.6rad/s2. The total revolutions that are made are

Î”Î¸=1/2Î”Ï‰t=748rads, so748rads/2Ï€=1.2x102revolutions