A flywheel rotates with a uniform angular acceleration. Its angular velocity increases from 20 pi rad/s to 40 pi rad/s in 10 seconds. How many rotations did it make in this period?

A flywheel rotates with a uniform angular acceleration. Its angular ve

1.	A flywheel rotates with a uniform angular acceleration. Its angular velocity increases from 20 pi rad/s to 40 pi rad/s in 10 seconds. How many rotations did it make in this period?
Answer» 80 100 120 150 Solution :As `OMEGA = omega_(0) + alpha t implies 40 pi = 20 pi + alpha xx 10` or `alpha = 2pi "rad/s"^(2)` As `omega^(2) - omega_(0)^(2) = 2 alpha theta implies (40pi)^(2) - (20PI)^(2) = 2 xx 2 pi theta` or `theta = (1200 pi^(2))/(4 pi) = 300 pi` No. of ROTATIONS COMPLETED = `(theta)/(2pi) = (300 pi)/(2pi) = 150`