A horizontal true centrifugal casting process is used to make brass bushings with the

following dimensions: length $=10cm,$ outside diameter $=15cm,$ and inside diameter $=12cm.$

$($a$)$ Determine the required rotational speed in order to obtain a G$-$factor of $70.($b$)$ When

operating at this speed, what is the centrifugal force per square meter $($Pa$)$ imposed by the

molten metal on the inside wall of the mold?