A$($n$)1\mathrm{.}8-$kg copper block is given an initial speed of $4\mathrm{.}2$ m$/$s on a rough horizontal surface. Because of friction, the block finally comes to rest.

$($a$)$ If the block absorbs $85\%$ of its initial kinetic energy as internal energy, calculate its increase in temperature.

$$C

$($b$)$ What happens to the remaining energy?

It becomes chemical energy.It is so minute that it doesn't factor into the equation.$$It is absorbed by the horizontal surface on which the block slides.It vanishes from the universe.