Angular Momentum of a Baseball/MasteringPhysics Tech Support

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Homework Help Overview

The problem involves calculating the angular momentum of a baseball, treated as a uniform solid sphere, given its diameter, mass, and angular velocity. The original poster expresses frustration with feedback from MasteringPhysics despite feeling confident in their understanding of the problem.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to apply the moment of inertia formula for a solid sphere and the angular momentum equation, but questions arise regarding the use of diameter versus radius in their calculations.

Discussion Status

Some participants have engaged in clarifying the original poster's approach, specifically questioning whether the diameter was mistakenly used instead of the radius. There is an acknowledgment of a potential oversight without reaching a consensus on the correct calculation.

Contextual Notes

The original poster mentions a requirement for significant figures and expresses concern about the simplicity of the problem, indicating a possible mismatch between their understanding and the expectations of the homework platform.

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.
 
Physics news on Phys.org
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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