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Moment of Inertia and kinetic energy question

  • Thread starter kpengin
  • Start date
  • #1
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Homework Statement


The flywheel of a gasoline engine is required to give up 550 of kinetic energy while its angular speed decreases from 720 to 400 .
What moment of inertia is required?


Homework Equations


K=(1/2)Iw^2


The Attempt at a Solution


K=550J
I'm not sure how to get the w value since the velocity is changing.
I tried:
550=(1/2)I(320)^2
then solving for I
I=0.0107
but this is not correct.

Homework Statement





Homework Equations





The Attempt at a Solution

 

Answers and Replies

  • #2
Doc Al
Mentor
44,882
1,130
I tried:
550=(1/2)I(320)^2
The right hand side is incorrect. You want Δ((1/2)Iw^2), not (1/2)I(Δw)^2.
 

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