Download Unit 13: Periodic Motion

AP Physics: Mechanics
Periodic Motion: Chapter 13
Objectives
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Students will learn that:
o Periodic motion is motion that repeats itself in a definite cycle. It occurs whenever a
body has a stable equilibrium position and a restoring force that acts when it is
displaced from equilibrium.
o Period is the time for one cycle. Frequency is the number of cycles per unit time.
Angular frequency is 2𝜋 times the frequency.
o If the net force is a restoring force that is directly proportional to the displacement, the
motion is called simple harmonic motion (SHM).
o The circle of reference construction uses a rotating vector called a phasor, having a
length equal to the amplitude of the motion.
o The angular frequency, frequency, and period in SHM do not depend on the amplitude,
but only on the mass and force constant.
o In SHM, the displacement, velocity, and acceleration are sinusoidal functions of time.
o Energy is conserved in SHM.
o In angular SHM, the frequency and angular frequency are related to the moment of
inertia and the torsion constant.
o A simple pendulum consists of a point mass at the end of a massless string of length. Its
motion is approximately SMH for small amplitude. The angular frequency, frequency,
and period depend only on gravity and length.
o A physical pendulum is a body suspended from an axis of rotation a distance from its
center of gravity.
o When a damping force proportional to velocity is added to a simple harmonic oscillator,
the motion is called a damped oscillation.
o When a sinusoidally varying driving force is added to a damped harmonic oscillator, the
resulting motion is called a force oscillation..
Homework:
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Read the Chapter
PP 507-513 #’s 1,3,5,7,9,15,19,25,27,31,33,41,43,45,49,57,61,63,69,75,89,91
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