8. In tetrahedron $ABCD$, the dihedral angle between faces $ABC$ and $BCD$ is $30^{\circ}$, the area of $\triangle ABC$ is $120$, the area of $\triangle BCD$ is $80$, and $BC=10$. Find the volume of the tetrahedron.
(1992 American Competition Problem)
8. Draw $D P \perp$ plane $A B C$ at $P$, and draw $D H \perp B C$ at $H$. Connect $P H$, then $P H \perp B C, \angle D H P=30^{\circ}$. Given $S_{\triangle B C D}=$ $80, B C=10$, we get $D P=\frac{1}{2} D H=8$, thus $V_{A B C D}=\frac{1}{3} D P \cdot S_{\triangle A B C}=320$.