Question $4$

n a mining operation, iron ore is dumped into a funnel$-$shaped hopper that fills box ca rain. The inside of the hopper wears out rapidly because the impact of the hard ore $p$ deforms the hopper surface. A change of surface material is considered. Find which the better choice of hopper surface material is:

teel: $($AISI $1018)$ with $S_y=380$MPa,$E=207$GPa

rass: $S_y=119$MPa,$E=100$GPa

ubber: $S_u=40$MPa,$E=0\mathrm{.}004$GPa