A fan makes 2400 rpm. If after it is switched off, it comes to rest in 10 s, then find the number of timesit will rotate before it comes to rest after it is switched off.

Given,    f=2400rpm=240060=40 Hz∵  ω0=2πf=80πqrads-2Now,   θ=ωd+ω2t+⇒  θ=80π+02×10=400πrad∴ Fan will turn angle 400 πafter it is switched off.⇒ The number of rotation   =θ2π=400π2π=200