Question

A person gives a box a shove so that it slides up a ramp, then reverses its motion and slides down. Part A: What is the direction of the force of friction?

1) Up the ramp
2) Down the ramp
3) Opposite to the motion
4) In the same direction as the motion

Answer 1

The direction of the force of friction is opposite to the motion of the box; up the ramp as it slides up, and down the ramp as it slides down.

Step-by-step explanation:

The force of friction always acts in the direction opposite to the motion of an object. Therefore, when a box is given a shove up a ramp and then slides back down, the force of friction acts up the ramp while the box is sliding up, and down the ramp while the box is sliding down. This is consistent with the fundamental understanding of friction provided by physics, that friction opposes the relative motion between two surfaces in contact.