Question $\backslash$#$1$

Bushings for a certain application are made of brass using a horizontal centrifugal casting. The bushings are $10$ cm long with inside and outside diameters of $12$ cm and $15$ cm respectively. Knowing the density brass is $\backslash (8\mathrm{.}62\backslash$mathrm$\{$~g$\}/\backslash$mathrm$\{$cm$\}3\backslash ),$

$($a$)$ How fast the mold should be rotated to achieve $70$ g $.$

$($b$)$ Calculate the pressure exerted to the inner wall of the mold by the molten metal.