A hand$-$driven tire pump has a piston with a $2\mathrm{.}50$ cm diameter and a maximum stroke of $28\mathrm{.}0$ cm$.$

$($a$)$

How much work $($in J$)$ do you do in one stroke if the average gauge pressure is $2\mathrm{.}40105$ N$/$m$2($about $35$ psi$)?$

J

$($b$)$

What average force $($in N$)$ do you exert on the piston, neglecting friction and gravity?

N