Question

2. On the spin cycle on a washing machine, the drum holding the clothes goes from zero to 180 rpm (revolutions per minute) in 8.0 seconds. (Hint: Be sure to change rpm to radians/sec.)

(a) What is the angular acceleration (in radians/sec2) during this time period?

(b) How many revolutions does it take for the drum to reach 180 rpm?

Answer 1

1 revolution=2π radians
1 minute = 60 seconds

(a)
Angular acceleration
= 180 rpm/8 s
=22.5 rpm / s
= 22.5*(2π) radians/60s /s
=3π/4 rad/s²

(b)
No. of revolutions
=average angular speed * time
=(0+180)/2 rpm * (8/60) min
= 12 revolutions