1. The problem statement, all variables and given/known data alright, so i'm trying to find the rotational inertia of a urethane longboard wheel, and i need to integrate a section of it that looks like a truncated annular cylinder that looks something like this if you cut it in half 2. Relevant equations just to be sure that i don't plagiarize or anything, i was hoping for more of a hint instead of a straight up answer if possible... question mark 3. The attempt at a solution i first derived the equation for the rotational inertia of an annular cylinder (I=(1/2)M(R1^2+R2^2), then i used M=(density)V to find the mass, but i can't find the density unless i dump the wheel into a wet measure filled with water, and i really don't wanna do that. any ideas?