Using the result Пa2, determine the volume of a cone of height h and radius a. Find the position of its centre of mass.
Orient the cone with the vertex at the origin and the axis along the y-axis.
$\displaystyle M=\int_{0}^{h}{\rho}{\pi}\left(\frac{a}{h}y\right) ^{2}dy=\frac{1}{3}{\rho}{\pi}a^{2}h$
$\displaystyle M_{y=0}=\int_{0}^{h}{\rho}y{\pi}\left(\frac{a}{h}y \right)^{2}=\frac{1}{4}{\rho}{\pi}a^{2}h^{2}$
$\displaystyle \overline{y}=\frac{3h}{4}$
Center of mass is on axis of cone, 3/4 the length of the height from the vertex, or 1/4 of the length of the height from the base.