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Physical Manifestations of Periodic Functions. Matthew Koss College of the Holy Cross July 12, 2012. IQR Workshop: Foundational Mathematics Concepts for the High School to College Transition. Simple Block and Spring. Data Studio 500. Simple Harmonic Motion.
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Physical Manifestations of Periodic Functions Matthew Koss College of the Holy Cross July 12, 2012 IQR Workshop: Foundational Mathematics Concepts for the High School to College Transition
Simple Harmonic Oscillations A Amplitude w t + f Phase (radians)/Angle (radians) f Phase Constant (radians) w Angular Frequency (rad/s) T Period (s) f Frequency (Hz)
Review A Periodic Function (sine or cosine) is the Recorded History of the Oscillations of an object attached to a spring.
Position, velocity, and acceleration If you know calculus
Zero Offset • Oscillations do not always occur about the zero point. • To account for this, there is one additional term called the zero offset which is middle value in the oscillations. • So, more completely:
y(t) A A y(t) y2 y1 y2(t) y1(t) Illustration
Physical Pendulum Same as a simple pendulum, but… axis cm
Tangent on Traveling Waves A wave is a disturbance in position propagating in time. Many traveling waves are periodic in both position and time, e.g.
Mathematical Relationships In general: Specifically: Periodic Sine Waves A Amplitude kx-wt+f Phase (radians) w Angular Frequency (rad/s) T Period (s) f Frequency (Hz) k (Angular) Wave number Wavelength
Waves and Oscillations Compared An oscillation in time is a “history” of a wave at a particular place. An oscillation in space is a “snapshot” of a wave at a particular time,
Sum of Two Traveling Waves Makes Standing Waves Last Slide of Digression
Guitar Strings The strings on a guitar can be effectively shortened by fingering, raising the fundamental pitch. The pitch of a string of a given length can also be altered by using a string of different density.
Beats If the two interfering oscillations have different frequencies they will superimpose, but the resulting oscillation is more complex. This is still a superposition effect. Under these conditions, the resultant oscillation is referred to as a beat.
Beat Frequency Mathematics fBeat= f1 -f2
Amplitude (I) of Sound Oscillations The loudness of a sound is much more closely related to the logarithm of the intensity. Sound level is measured in decibels (dB) and is defined as: I0 is taken to be the threshold of hearing:
Web References/Resources • PhET Simulations • http://phet.colorado.edu/en/simulations/category/new • Springs • http://phet.colorado.edu/en/simulation/mass-spring-lab • Rotation • http://phet.colorado.edu/en/simulation/rotation • Atomic Oscillation • http://phet.colorado.edu/en/simulation/states-of-matter • Pendulum • http://phet.colorado.edu/en/simulation/pendulum-lab • Normal Modes • http://phet.colorado.edu/en/simulation/normal-modes • Making Waves • http://phet.colorado.edu/en/simulation/fourier • Video Physics • http://itunes.apple.com/us/app/vernier-video-physics/id389784247?mt=8 • Physics Toolkit • http://physicstoolkit.com/ • MacScope & Physics2000 • http://www.physics2000.com/Pages/Downloads.html • Audacity • http://audacity.sourceforge.net/download/