30 multiple-choice questions covering all 9 topics of Unit 2 — Newton's laws, free-body diagrams, gravity, friction, springs, and circular motion. Use g = 10 m/s².
Always start with a free-body diagram. Even when not explicitly asked, sketching one helps you identify every force in play and avoid forgetting one.
Newton's third-law pairs act on different objects. If you're tempted to call two forces a third-law pair but they're both on the same object — they're not. They're either balanced forces or unrelated.
Normal force is NOT always equal to mg. On inclines, in elevators, or when something pushes down on the object, F_N changes. Re-derive it from ΣF = ma each time.
Centripetal force is a role, not a new force. When you see circular motion, ask: which real force (tension, gravity, friction, normal) points toward the center?