Problem 7-65 Energy cons. with friction

A box of apples (mass 22kg) slides down a ramp inclined at 44 to the horizontal. The fiction force on the box has a magnitude of 79N. If the box starts from rest and slides 2.5m 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) 2.0×102J   (b) 1.8×102J   (c) 2.0×102J ]


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

Four possible FBD; A, B, C, D.

(A)

(B)

(C)

(D)