$2.[30$ Pts$.]$ A $25-$mm$-$diameter steel shaft of hardness HB$420$ rotates at $1750$ rpm in a $40$ mm $-$long plain bronze bushing with an average radial load of $500$ N $.$ Estimate the time it would take to remove $0\mathrm{.}05$ mm of bushing material by adhesive wear if the lubrication were suddenly lost assuming a uniform wear rate around the bushing. $[$Note: the principal elements in bronze are copper $\backslash ((\backslash$mathrm$\{$Cu$\})\backslash )$ and tin $\backslash ((\backslash$mathrm$\{$Sn$\})\backslash ).$ Also, watch units as noted in footnote on p$\mathrm{.}389]$