The spin dryer of washing machine rotating at 15 rps slows down to 5 rps after making 50 rotations. Find the its angular acceleration.

Explanation

Given : `n_(0)=15" r.p.s., n = 54 r.p.s.,"`
No. of revolutions = 50
`:." "omega=2 pin`.
`:." "`Initial angular velocity, `omega_(0)`
`=2 pixx 15` rad/s
Final angular velocity , `omega=2pixx5xx`day/s
In onel revolution, angular displacement
`=2pi`
In 50 revolution, angular displacement `=2pixx50`
We know that,
`omega^2 = omega_(0)^2++2 alpha theta`
`( 2 pi xx 5)^2 =(2 pi xx 15)^2 + 2 alpha xx ( 2 pixx 50)`
`100 pi^2 = 900 pi^2`
` alpha = - 12.56"ead/s"^2`
The negative sign indicates that the angular acceleration is directed oppsite to the angular velocity.