Practice simple harmonic motion, period, frequency, springs, pendulums, and energy in SHM. Quiz one topic at a time or take the whole unit.
The idea each topic turns on, and the mistake students make most often.
Key ideaSimple harmonic motion happens when the restoring force is proportional to the displacement and opposite to it. The acceleration is largest at the extremes and zero at equilibrium.
Common mistakeThinking the speed is largest at the extremes, or the acceleration largest at equilibrium. It is the other way around.
Key ideaThe period is the time for one full cycle and the frequency is 1/T. For SHM, the period does not depend on the amplitude.
Common mistakeThinking a larger amplitude makes the period longer.
Key ideaFor a mass on a spring, T = 2π√(m/k): more mass gives a longer period, and a stiffer spring gives a shorter one.
Common mistakeExpecting g or the amplitude to change the period. Neither does, even for a vertical spring.
Key ideaA simple pendulum’s period, T = 2π√(L/g), depends only on its length and on g, for small angles.
Common mistakeThinking a heavier bob changes the period. It doesn’t.
Key ideaThe total energy, ½kA², stays constant. It is all potential energy at the extremes and all kinetic energy at equilibrium.
Common mistakeForgetting that the energy depends on A², so doubling the amplitude quadruples the energy.
This is one of the 26 questions in the Unit 7 quiz.
Which pair contains two common examples of simple harmonic motion?
Answer: A. A pendulum swinging through small angles and a mass on a spring
A pendulum swinging through small angles and a mass on a spring are the classic examples of simple harmonic motion.
AP-style FRQs for this unit. Students score themselves point by point against a rubric and see a full solution.
