
Moment of Inertia
What is the moment of inertia about the axis of a cone of uniform density, D, of base radius, a, and altitude, h.
The answer is supposed to be expressed in terms of a, h, and the mass of the cone.
But my answer does not make use of h!
I get:
$\displaystyle 6/5 a^2 M$

Depends on the axis, if it's the axis going through the tip of the cone and the center of the base (usually called the zaxis) then h doesn't enter into the equation because of symmetry:
zaxis: I = (3/10)Ma^2
http://wiki.answers.com/Q/Moment_of_inertia_of_cone