Calculate the angular momentum

  • Thread starter Exustior
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  • #1
Exustior
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Homework Statement


A batter swings a 0.9 m long bat. Calculate the angular momentum of the bat relative to its axis of rotation. Assume the bat has a mass of 0.6 kg and rotates at 3 rad / s
(Hint: Approximate the bat by a rod, or a long thin cylinder, and find the moment of inertia.)
Answer in (N m)


Homework Equations


I=mr^2
ω=v/r
v=ωr
L=Iω



The Attempt at a Solution


L=Iω
I=mr^2
so L=(0.6)(.9^2)(ω)
ω=angular velocity is 3 rad/s
so L=(.6)(.9^2)(3rad/s)= Wrong answer
 
Last edited:

Answers and Replies

  • #2
BruceW
Homework Helper
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Hey, welcome to physicsforums!
uh, the moment of inertia formula you have used is not correct for this problem. The inertia I=(0.6)(0.9)^2 would suggest the mass of the bat is concentrated at the end of the bat. But it looks like they want you to assume the bat is a long thin cylinder, of uniform density. So either you can look up the moment of inertia for this kind of object, or derive it yourself, if you have time.
 
  • #3
Exustior
2
0
Hey, welcome to physicsforums!
uh, the moment of inertia formula you have used is not correct for this problem. The inertia I=(0.6)(0.9)^2 would suggest the mass of the bat is concentrated at the end of the bat. But it looks like they want you to assume the bat is a long thin cylinder, of uniform density. So either you can look up the moment of inertia for this kind of object, or derive it yourself, if you have time.
Thanks!
I got it I was using the wrong formula.
 

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