Question

multiple choice question
kinetic friction is the force exerted on one surface by a second surface when the two surfaces rub against each other because one or both of the surfaces
are moving.
have just stopped moving.
are stationary.
are about to move.
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Explanation:

Kinetic friction occurs when two surfaces are in relative motion (i.e., moving against each other). Static friction is when surfaces are stationary or about to move. Once they stop moving, friction type changes. So kinetic friction is when surfaces are moving.

Answer:

are moving.