Question 20 • Mad 2017 Phy Sci B -33 SS
Friction resists motion between surfaces that are touching, so it is a contact force—not a force that acts from a distance. At a microscopic level, bumps and ridges on the surfaces interact and help produce friction. Therefore, “Friction resists motion,” “Friction is a contact force,” and “Friction is caused by microscopic bumps and ridges on surfaces” are correct; friction does not let objects slide without resistance.
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