Angular Momentum of a Baseball/MasteringPhysics Tech Support

AI Thread Summary
To calculate the angular momentum of a baseball with a diameter of 7.3 cm and mass of 150 g spinning at 230 rad/s, the moment of inertia formula for a uniform solid sphere, I = (2/5)MR^2, is applied. The radius must be converted from diameter, leading to a calculation of I = 0.00031974 J. Subsequently, angular momentum is calculated using L = Iω, resulting in L = 0.0735402 J·s. The user expresses frustration with MasteringPhysics feedback, suspecting a mistake in their calculations, but it is clarified that the issue may stem from a simple oversight rather than a fundamental misunderstanding. Accurate unit conversion and attention to detail are emphasized in resolving such problems.
Keith Moffet
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Homework Statement


A 7.3-cm-diameter baseball has mass of 150 g and is spinning at 230 rad/s .
Treating the baseball as a uniform solid sphere, what is its angular momentum?

I'm about to pull my hair out because I feel like I understand everything about this problem perfectly and yet I'm still getting back sass from MasteringPhysics.
But, hey I'm not the smartest guy out there so I've probably actually got it wrong.

Homework Equations


Moment of inertia of a uniform solid sphere:
2/5*MR^2

L=Iω

The Attempt at a Solution


.4*.15*.073^2=.00031974J=I
Iω=.00031974*230=.0735402J*s=L

This is apparently wrong; yes I've attempted giving them the 2 significant figures they asked for.

Including unit conversion, this seems like nothing more than physics flavored 9th grade algebra, which is exactly why I'm worried enough about it to come seek help.
 
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Did you use the diameter where you meant to use the radius?
 
Thanks for replying! I'm an idiot.
 
Keith Moffet said:
I'm an idiot.
No, just an oversight. Easy to do.
 
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