Unit 2 · 2.9 — Circular Motion

Everything to learn here

• Concept: Uniform circular motion requires a continuous net force directed toward the center of the circle, changing the velocity's direction but not its magnitude.
• Concept: Centripetal force is not a distinct physical force; it is the label for the net radial force supplied by existing forces like tension, friction, or gravity.
• Concept: In vertical circular motion, the normal force or tension varies depending on the position, while gravity remains constant.
• Concept: The velocity vector is always tangent to the circular path, while the centripetal acceleration vector points radially inward.
• Equation: $$ac=\frac{v}{r}\text{(Centripetal Acceleration)}$$
• Equation: $$\sum Fc=m\cdot \frac{v}{r}\text{(Newton’s Second Law applied to uniform circular motion)}$$
• Vocabulary: Centripetal Acceleration — The radial acceleration directed toward the center of a curved path.
• Skill: Translation Between Representations — Drawing accurate force vectors for objects in circular paths (e.g., roller coasters, banked curves) to prove the net force points radially inward.
• Skill: Describe circular orbits by relating orbital period and radius using Kepler's third law.

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