A hand$-$driven tire pump has a piston with a $2\mathrm{.}50-$cm diameter and a maximum stroke of $30\mathrm{.}0$ cm$.($a$)$ How much work do you do in one stroke if the average gauge pressure is $2\mathrm{.}40105$N$/$m$22\mathrm{.}40105$N$/$m$2($about $35$ psi$)?($b$)$ What average force do you exert on the piston, neglecting friction and gravitational force?