Answer:
2.17 s
Explanation:
Here, w0 = 33.3 rpm = 33.3 /60 rps
= 2 × pi × 33.3 / 60 rad/ s
= 3.4854 rad / s
w = 78 rpm = 78 / 60 rps
= 2 × pi × 78 / 60 = 8.164 rad / s
a = 2.15 rad/s^2
Use first equation of motion for rotational motion
w = w0 + a t
8.164 - 3.485 = 2.15 × t
t = 2.17 s
