Data : f1 = 60 rpm = \(\frac{60}{60}\) rev/s = 1
rev/s, f2 = 180 rpm = \(\frac{180}{60}\) rev/s = 3
rev/s, t = 20 s
The angular acceleration in SI units,
OR
Using non SI units, the angular frequencies are ω1 = 60 rpm = 1 rps and ω2 = 180 rpm = 3 rps.