Physics B
Notes: Oscillation
Mechanical Wave
Definition:
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Wave types: transverse
Definition:
Draw a wave; label the parts
Examples
Wave types: longitudinal
Definition:
Speed of a wave
Equation 1:
Equation 2:
Examples
Period of a wave
Equation:
Reflection of waves
Definition:
.
Problem: Sound travels at approximately
340 m/s, and light travels at 3.0 x 108 m/s.
How far away is a lightning strike if the
sound of the thunder arrives at a location 2.0
seconds after the lightning is seen?
Characteristics of Fixed-end reflection
Characteristics of Open-end reflection
Problem: The frequency of an oboe’s A is
440 Hz. What is the period of this note?
What is the wavelength? Assume a speed of
sound in air of 340 m/s.
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Refraction of waves
Definition:
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Principle of Superposition
Definition:
What can change when a wave refracts?
What never changes when a wave refracts?
Sound
What type of wave is sound?
Constructive interference
Definition:
How does the oscilloscope display a pure
tone?
Picture of waveforms undergoing
constructive interference:
What does a Fourier transform look like
for a pure tone?
Destructive interference.
Definition:
How does the oscilloscope display a
complex tone?
Picture of waveforms undergoing
destructive interference:
What does a Fourier transform look like
for a complex tone?
Sample Problem: Draw the waveform
from its two components.
Doppler Effect
Definition:
Approaching sound has ________ pitch.
Retreating sound has ________ pitch.
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Standing Wave
Definition:
Open-end standing waves
1st harmonic
What role does reflection play in
formation of a standing wave?
2nd harmonic
What role does superposition play in a
standing wave?
3rd harmonic
Fixed-end standing waves
1st harmonic
Mixed standing waves
1st harmonic
2nd harmonic
2nd harmonic
3rd harmonic
3rd harmonic
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Sample Problem
How long do you need to make an organ
pipe that produces a middle C (256 Hz)?
The speed of sound in air is 340 m/s.
A) Draw the first harmonic.
Resonance
Definition:
Beats
Definition:
B) Calculate the pipe length.
Drawing:
C) What is the wavelength and
frequency of the 2nd harmonic?
Diffraction
Definition:
Double-slit or multi-slit diffraction
Equation:
Sample Problem
How long do you need to make an organ
pipe whose fundamental frequency is a Csharp (273 Hz)? The pipe is closed on one
end, and the speed of sound in air is 340
m/s.
A) Draw the fundamental.
Single slit diffraction
Equation:
Sample Problem
Light of wavelength 360 nm is passed
through a diffraction grating that has
10,000 slits per cm. If the screen is 2.0 m
from the grating, how far from the
central bright band is the first order
bright band?
B) Calculate the pipe length.
C) What is the wavelength and
frequency of the 2nd harmonic?
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Sample Problem
Graph:
Light of wavelength 560 nm is passed through
two slits. It is found that, on a screen 1.0 m
from the slits, a bright spot is formed at x =
0, and another is formed at x = 0.03 m? What
is the spacing between the slits?
x(m)
t
Definitions:
Amplitude
Sample Problem
Light is passed through a single slit of width
2.1 x 10-6 m. How far from the central bright
band do the first and second order dark bands
appear if the screen is 3.0 meters away from
the slit? Assume 560 nm light.
Period
Frequency
Ideal Springs
What makes springs ideal?
Periodic Motion
Definition:
Hooke’s Law
Equation:
What are mechanical devices that
undergo periodic motion called?
Period of a spring
Equation:
Simple Harmonic Motion
Definition:
Sample Problem
Calculate the period of a 300-g mass
attached to an ideal spring with a force
constant of 25 N/m.
Simple Harmonic Oscillators
Definition:
Examples:
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Sample Problem
A 300-g mass attached to a spring
undergoes simple harmonic motion with a
frequency of 25 Hz. What is the force
constant of the spring?
Sample problem
A spring of force constant k = 200 N/m is
attached to a 700-g mass oscillating
between x = 1.2 and x = 2.4 meters.
Where is the mass moving fastest, and
how fast is it moving at that location?
Sample Problem
An 80-g mass attached to a spring hung
vertically causes it to stretch 30 cm from
its unstretched position. If the mass is
set into oscillation on the end of the
spring, what will be the period?
Sample problem
A spring of force constant k = 200 N/m is
attached to a 700-g mass oscillating
between x = 1.2 and x = 2.4 meters. What
is the speed of the mass when it is at the
1.5 meter point?
Sample Problem
You wish to double the force constant of
a spring. You
A. Double its length by connecting it to
another one just like it.
B. Cut it in half.
C. Add twice as much mass.
D. Take half of the mass off.
Sample problem
A 2.0-kg mass attached to a spring
oscillates with an amplitude of 12.0 cm
and a frequency of 3.0 Hz. What is its
total energy?
Conservation of Energy
Where does maximum kinetic energy
occur?
Where does maximum potential energy
occur?
Where does maximum total energy occur?
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Pendulums
When is a pendulum a good approximation
of a simple harmonic oscillator?
Pendulum Forces
Equation:
Sample problem
Predict the period of a pendulum
consisting of a 500 gram mass attached
to a 2.5-m long string.
Sample problem
Suppose you notice that a 5-kg weight
tied to a string swings back and forth 5
times in 20 seconds. How long is the
string?
Sample problem
The period of a pendulum is observed to
be T. Suppose you want to make the
period 2T. What do you do to the
pendulum?
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Physics B
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Notes: Oscillation
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Name:_________________
Bertrand