When the power is turned on, the unit attains the rated speed in 5 seconds & when the power is turned off, the unit comes to rest in 90 seconds. Assuming uniformly accelerated motion, determine the number of revolutions the unit turns: i) to attain the rated speed & ii) to come to rest.

i) acceleration

$N2 = 1740 rpm$ (final speed)

$T = 5 s$ (time of acceleration)

$N1 = 0$ (initial speed)

ii) retardation

$T = 90 s$ (time of retardation)

$$N1 = 1740 rpm$$

$$N2 = 0$$

Solution:

i)

$w2 = 2πN_2/60 = 182.2 rad/s \\ w1 = 0$

Using first …