The speed of an electric motor is increased uniformly from 1200 to 1350 rpm in a time of 1.5 s. Find (a) the angular acceleration, (b) the number of revolutions turned during this time.
A winding drum is accelerated from 480 to 840 rpm in a time of 2 s. Acceleration continues at the same rate for a further 4 s after which the drum continues rotating at a steady speed. Calculate the time taken to complete the fi rst 200 revolutions.