Angular displacement with constant acceleration

[lc99]

Homework Statement

Homework Equations

displacement = .5(wi+wf)*t
wi =0
wf=5 rev / sec
t=10

The Attempt at a Solution

displacement = 5/2*10= 25 revolutions

I know it is simple, but I am not sure if i heard right that the answer is actually 50 revolutions. Did i do something wrong?

 

[TSny]

You are right. Note that if the turntable rotated at a steady rate of 5 rev/s it would rotate through 50 rev in 10 s. But in your problem, the turntable only reaches 5 rev/s at the very end of the 10 s time interval. So there is no way it could make 50 rev in 10 s.