Question

10. A 90 kg box is sliding across a surface at a constant velocity while experiencing a rightward applied

force of 40 N. Calculate the force of friction acting on the box.
A. -40N
B. +40N
C.-2.5 N
D. 0 N

Answer 1

I’m pretty sure that the answer is D

Answer 2

If the box is moving at constant velocity, net force must be zero, so:

F + fr = 0

fr = -F

fr = -40 N