feed to be reduced to fixed dimensions $($iii$)$ heat sensitive$.$ Justify the selection

Q$.2($b$)($i$)$ Estimate the Power required to convert feed particles of $51mm$ dia to $3\mathrm{.}2mm$ dia particles. Let mass flow rate be $100$ ton$/$hr and $W_1$ is $12\mathrm{.}74$

$($ii$)$ In a grinding mill, time taken to diminish $20\%$ of a feed material with initial mass