Angular acceleration problem

  • Thread starter seboastien
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  • #1
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Homework Statement



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?

Homework Equations



chain rule

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
 

Answers and Replies

  • #2
rock.freak667
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Well you should know that α= -2ω2 means that dω/dt = -2ω2

which is an easily solvable DE once you 'separate the variables' i.e. put all the things with ω on one side and t on the other then integrate both sides.
 
  • #3
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But then I end up with t=1/2w, how do I find the rest of the answer?
 
  • #4
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Someone please help me!!!!
 
  • #5
rock.freak667
Homework Helper
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But then I end up with t=1/2w, how do I find the rest of the answer?

I now saw that you have ω and θ so forget my above post and replace α with ω*dω/dθ and integrate again. Do not forget the constant of integration which you can find with the conditions they gave you.
 
  • #6
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Yes, that was my problem all along... I forgot to add the constant!! Thanks.
 

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