the tub of a washing machine is initially at rest. when the spin cycle begins, it begins to rotate. In the first 2.80 s, it makes 3 complete revolutions. what is its final angular velocity?

Answer 1

velocity increases linearly from 0 to final so average angular velocity is half the final
average angular velocity = 3*2 pi radians / 2.8 seconds
so
final = (12 pi/2.8) radians/second

Answer 2

algebra why it works :)
v = a t
final V = a T where T is final t
d = (1/2) a t^2
final D = (1/2) V/T * T^2 = (1/2) V T