a pulley of 5cm radius on a motor is turning at 30 rev/s and slows down uniformly to 20 rev/s in 2s. calculate the angular acceleration of the motor number of revolution it makes in this time and lenght of belt it winds in this time

Answer 1

ω= ω₀- εt
2πn=2πn₀ - εt
ε=2π(n₀-n)/t =2π(30-20)/2=31.4 rad/s²
N= εt²/4π = 31.4•2²/4π =10 rev
L=2πR•N =2π•0.05•10 =3.14 m