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bcjochim07
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Homework Statement
A dumbbell consists of two mass points of equal mass m at opposite ends of a rigid rod of length l and negligible mass. Calculate the angular momentum of this dumbbell as it rotates with constant angular velocity [tex]\omega[/tex] about an axis that makes a constant angle [tex]\theta[/tex] with the dumbbell and passes through its center of mass.
Homework Equations
In my calculation, I'll use r=l/2
The Attempt at a Solution
I'm not sure if this is correct, but here's what I did:L = rXp
Since there are two masses:
L=[tex]\Sigma[/tex]Li
=rXp1 + rXp2 = m[(rXv1)+ (rXv2)]
=m[(rX(rsin[tex]\theta[/tex][tex]\omega[/tex])+rX(rsin[tex]\theta[/tex][tex]\omega[/tex]]
=mrsin[tex]\theta[/tex][rX[tex]\omega[/tex] + rX[tex]\omega[/tex]]
||L||=mrsin[tex]\theta[/tex][r[tex]\omega[/tex]sin[tex]\theta[/tex]+r[tex]\omega[/tex]sin[tex]\theta[/tex]]
=2mr2sin2[tex]\theta[/tex][tex]\omega[/tex], r=l/2
L=(1/2)ml2sin2[tex]\theta[/tex] [tex]\widehat{n}[/tex] ;
where [tex]\widehat{n}[/tex] is a unit vector perpendicular to both r and [tex]\omega[/tex]
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