starting from rest, a $5\mathrm{.}0$ kg block slides $2\mathrm{.}5$ m down a roguh $23$ degree incline in $3\mathrm{.}0$s$.$The acceleration of gravity is $9\mathrm{.}81$ m$/$s$2.$ Find the work done by the force of gravity. Answer in units of J$.($b$)$ Find the change in mechanical energy due to friction. Answer in units of J$.$