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Old Aug 18th 2011, 04:37 AM   #1
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find angular velocity of system PLEASE!

1. The problem statement, all variables and given/known data

angular acceleration of line a= -2w^2 rad/s

when theta=pi/6, w= 10 rad/s

what is angular velocity when theta= pi/3?

2. Relevant equations

chain rule

3. The attempt at a solution

w= e^-2theta is my answer, but I know this is wrong

I know that this question is really easy, but I just don't know how to get it
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Old Sep 21st 2011, 03:02 PM   #2
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Start with a= dw/dt and apply the chain rule: a= dw/d(theta) x d(theta)/dt. From this you can derive

2 a theta = w^2 + C, where C = an unknown constant

Substitute for a:

2 (-2 w^2)theta = w^2 + C

Rearrange:

w^2(1+ 4 theta) + C = 0

Given that w = 10 when theta = pi/6 lets you find the value for C. Then solve for w when theta = pi/3.
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