Question

A pulley of 5 cm radius on a motor is turning at 30 rev/s and slows down uniformly to 20 rev/s in 2 s.
Calculate (a) the angular acceleration of the motor (b) the number of revolutions it makes in this time, and
(c) the length of belt it winds in this time.​

Answer 1

Answer:

The angular velocities are given as,

ω1=1200rpm

ω1=40πrad/s

ω2=900rpm

ω2=30πrad/s

The angular acceleration is given as,

α=240π−30π

α=5πrad/s2

The angle is given as,

θ=ω1t+21αt2

θ=40π×2+21×5π(2)2

θ=90πrad

The numbers of revolutions are given as,

n=2π90π

n=45rev