# Problem 7-65 Energy cons. with friction

A box of apples (mass $22\; kg$) slides down a ramp inclined at $44^\circ$ to the horizontal. The fiction force on the box has a magnitude of $79\; N$. If the box starts from rest and slides $2.5\; m$ along the ramp, determine:

(a) the work done by friction
(b) the box's final kinetic energy (using conservation of energy)
(c) the thermal energy produced.

[Ans. (a) $-2.0\times 10^2 \;J$   (b) $1.8\times 10^2\; J$   (c) $2.0\times 10^2\; J$ ]

We need a good picture of the situation. Which drawing represents the problem?

(A)

(B)

(C)

(D)