Topic 2.9: Circular Motion

Name: _______________________________ Date: _______________ Period: _______

Key Ideas

• Constant SPEED in a circle still means accelerating, because velocity DIRECTION keeps changing.
• Centripetal acceleration: $a_c = \dfrac{v^2}{r}$, always directed toward the center.
• Centripetal force is not a new force — it's the net result of real forces (tension, gravity, friction, normal force) pointing toward the center: $F_{net} = \dfrac{mv^2}{r}$
• $T = 1/f$; $v = \dfrac{2\pi r}{T}$
• Kepler's Third Law (circular orbits): $T^2 \propto r^3$

Keep This Sheet!

These sheets build into your semester study guide. Keep them in order in a binder or folder — you'll want to flip back through them before quizzes, unit tests, and when AP exam review starts in the spring.