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

Explanation

` :. omega_(2) = omega_(1) +alphat :. 40 pi = 20 pi +10 alpha rArr a = 2 pi "rad/s"^(2)`
angular dispalcement
`theta = (omega _(2)^(2)-omega_(1)^(2))/(2alpha) = ((40pi^(2)) - (20pi)^(2))/(2xx2pi) = (1200pi^(2))/(4pi) = 300 pi `
Therefore number of rotations
` = theta / (2pi) = (300 pi)/(2pi) = 150`