Alright... I've been struggling with this derivation for QUITE some time, and I can't get a hold of my TA... so... I'm trying to derive the centre of mass of a truncated sphere. The final answer is cm= -(3h^2*(R-h/2)^2)/(4R^3-3Rh^2+h^3) Where R is the radius of the full sphere, and h is the height of the truncation. I'm trying to use a double integral, using the symmetry of the sphere, but I eother can't get the limits of integration right, or something in my math is wrong... I also have 2 other derivations to do in this lab that I'm struggling with... I'll throw them out too... cm = (8*pi*R^2)/(5*g*T^2) - This one, I can't seem to find relations that put all of these variables together (a rough start, I know...) And... The moment of inertia of the missing spherical cap. I(sc) = 3/2(M(cap)/3R-h)*(4/3R^2*h-Rh^2+h^3/5). Here, I'm trying to use rings of radius "r" and relate them to R and the z-axis, but again... something's not working out at all. (I may have the wrong idea on this problem to begin with... if only I lived close to my school... *sigh*) I know this is a lot, but ANY help would be appreciated..... even just a gentle push in the right direction for any of them... Thanks!