$29\mathrm{.}4.$ Solve Prob. $29\mathrm{.}3$ with $(a)=1\mathrm{.}1$ and $(b)=1\mathrm{.}6.$ Plot the results. Do they vary as you expected?

$295.$ Solve Prob. $29\mathrm{.}3$ with $=1\mathrm{.}3$ and with $S$ varying with $D_p^3$ for material coarser than $10-$mesh and with $D_p^2$ for the finer sizes. Are the results as you predicted?

$29\mathrm{.}6.$ What rotational speed, in revolutions per minute, would you recommend for a ball mill $1200mm$ in diameter charged with $75-mm$ balls?