Question

fill in the blank question
friction forces operate differently depending on whether there is between objects in contact or not. when objects in contact are moving
relative to each other, friction is involved. when there is a force tending to move one object against another, but the objects are not in
motion, friction forces exactly counterbalance that force.

Explanation:

Friction is classified based on relative motion. Kinetic friction occurs when there is motion between surfaces. Static friction acts when there is a tendency to move but no actual motion.

Answer:

relative motion, kinetic, static