Four objects, a thin right-cylindrical shell of radius R, a solid right-cylinder of radius R, a thin spherical shell of radius R, and a solid sphere of radius R, each have a mass M. Rank the moments of inertia of each of these object in increasing order from smallest (#1) to largest (#4). The two cylinders are rotated about their cylindrical axes and the two spheres are rotated about any diameter.

I said Solid sphere, spherical shell, solid cylinder, cylindrical shell...but apparently that is wrong.

I thought you were supposed to compare the equations that all look something like MR^2

Question

Four objects, a thin right-cylindrical shell of radius R, a solid right-cylinder of radius R, a thin spherical shell of radius R, and a solid sphere of radius R, each have a mass M. Rank the moments of inertia of each of these object in increasing order from smallest (#1) to largest (#4). The two cylinders are rotated about their cylindrical axes and the two spheres are rotated about any diameter.

I said Solid sphere, spherical shell, solid cylinder, cylindrical shell...but apparently that is wrong.

I thought you were supposed to compare the equations that all look something like MR^2

anonymous · Answer

Take a look here: http://en.wikipedia.org/wiki/List_of_moments_of_inertia

anonymous · Answer

Thats the list i used...I got the result I said in the question

anonymous · Answer

Let's take a closer look. 

Hollow Cylinder: $I=mr^2$
Solid Cylinder: $I = (mr^2)/2$
Hollow Sphere: $I=(2mr^2)/3$
Solid Sphere: $I=(2mr^2)/5$

$mr^2$ is the same in each, let's compare the fractions. 

Hollow Cylinder: $I=1$
Solid Cylinder: $I=1/2$
Hollow Sphere: $I=2/3$
Solid Sphere: $I=2/5$

This leads me to the same answer that you've got. SS, SC, HS, HC

anonymous · Answer

Actually. Double check your answer. 

2/3>1/2

anonymous · Answer

ah herp derp

anonymous · Answer

thanks a bunch

anonymous · Answer

Yep