how do u calculate the work done by friction of a box moving down a ramp?

Answer 1

The friction force up the ramp times the distance moved down the ramp. It is negative of course.
Work done by friction = - mu m g cos(ramp angle) * distance moved down ramp

Answer 2

what is "mu"?

Answer 3

The coeficient of friction

Answer 4

so if my mu is 0.042N
g is 9.8
m is 1.117 kg
ramp angle is 4
and distance is 1.0
then my answer is -0.46?

Answer 5

Yes