Question

A grinding wheel is initially rotating at 36 rad/s (radians per second) when its driving motor is turned off. If the wheel continues rotating at a constant rate of 3 rad/s^2, how long will the wheel take to rotate through an angle of 216 radians?

Answer 1

Ans. Wi= initial angulal velocity = 36 rad/s since, driving motor is turned off, the grinding wheel will start retard with anghalas acceleration, a=-3 rad/s2 & angular distance, o = 216 radians Using third equation of rotational motion we w ² = 240 wie - (36)2 + 2x(-3) x216 Wf = 0 rad/s = final angulal velocity using, first equation of rotational motion a Ws = Witat 0 = (+36) + (-3) xt -36=-3xt t=36 t = 12 sec = time taken by grinding whad to rotate through 216 radians