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Nanabit
Oct30-03, 01:24 PM
A rotating wheel requires 2.93 s to complete 37.0 revolutions. Its angular speed at the end of the 2.93 s interval is 97.1 rad/s. What is the constant angular acceleration of the wheel?

I know this should be easy. I'm just missing something. I figured 37 rev = 232 rad (=theta). Then I used the kinematic
Theta(f) = Theta(i)+(omega)(i)t+(1/2)(alpha)(t^2). But somehow it isn't working out. I know the answer should be around 15 or so but I keep getting 120 rad/sec^2!!

jamesrc
Oct30-03, 05:37 PM
You can't use your initial equation directly because you don't know the initial velocity yet. Use ωf = (ωi) + α*t; to find ωi. Then you can plug that in to your other constant acceleration question to find α. If I did it correctly, the acceleration should come out closer to 10 rad/s

Nanabit
Oct30-03, 05:50 PM
How can you use ùf = (ùi) + á*t to find ùi when you don't know what á is?

(alright well you know what those symbols should mean)

jamesrc
Oct30-03, 06:20 PM
You solve for ωi in terms of α and plug it into the other equation. It's a system of 2 equations with 2 unknowns.