<p>I just finished rotation problems and had a HARD time figuring out the equations for rotational inertia for different objects. I come to a problem and it has say a sphere or a rod or a disk or a cylinder, etc.........In my text there is a table of 9 different rotational inertias. DO you need to know ALL of those or just the general rotational inertia formula ?</p>
<p>ok, I am not sure what you mean by inertia, but I have learned about centripetal forces..is it the same thing?? Like, forces on a person going around a merry-go-around, etc. There's the normal force, force of gravity, and centripetal force.</p>
<p>It may be useful to memorize the most commonly seen moments of inertia: sphere and cylinder. I wouldn't worry about any of the other specific ones. Know the general formula for point masses.</p>
<p>No, it deals with rotation, it is not a force. It has to do rotation axis, and the mass distribution around it. </p>
<p>-Thanks FN. I would add 'thin' rod to that as I have seen that much.</p>
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In my text there is a table of 9 different rotational inertias. DO you need to know ALL of those or just the general rotational inertia formula ?
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<p>The specific ones are derived from integral calculus. If you're taking Calculus BC as well you should be able to understand how you derive them.</p>