Course Web Page for Phys1061
Fall 2005
Look for
solutions and discussions of quizzes right here.
Thursday, November 17, 2005: solution for quiz 9
Friday, November 11, 2005:solution for quiz 8
Try the following
experiment: Familiarize yourself with the Helmholtz resonance frequency of a
softdrink bottle of your choice. Then hold the bottom of the bottle against
your ear. That works best in a place where there is some white noise, like wind
blowing or, a fan, or some other source of broadband noise. You will hear the
parts of the noise which resonate with the Helmholtz resonator enhanced. This
was actually used in order to determine the frequency composition of sounds,
before we had electronic means of doing so.
Tuesday, November 08, 2005: solution for quiz 7
Wednesday, October 12, 2005: Solution for Quiz 6
In grading
your Quizzes:
Sound in air
moves at about 300 m/s, as many of you correctly recognized. However, there are
other objects which can move at speeds of this magnitude, or even faster:
Air planes,
rocket cars, the end of a whip ….
Anything
that creates a sonic boom is moving at more than the speed of sound.
That also
should answer why I did not give points for the suggestion that cars move at
this speed: seldom do we hear a sonic boom from a traveling car, with the
exception of experimental rocket cars for breaking speed records in the
Thursday, October 06, 2005: Solution for Quiz 5
Wednesday, September 28, 2005: solution for quiz 4
Remarks to
your answers:
- The force is directed
downward inplaces where the spring is compressed. This will be the case
anytime the mass is located above the equilibrium line.
- The amplitude or energy
is decreasing for a damped harmonic oscillator. Some of you answered speed and force. The problem with these answers is, that both, speed and
force are changing throughout the oscillation. What would it mean for them
to decrease, if they are changing all the time? You need to qualify this
as maximum speed or maximum force for it to become a
correct answer, since these characterize basically the amplitude in speed
and force. Those will decrease in a damped harmonic motion.
- The frequency of a harmonic
oscillator is not dependent on the amplitude.
That is one very important characteristic of the harmonic oscillator. Some
of you answered mass. While
this is true for a particular type of oscillator (the pendulum), it
certainly is not true for all harmonic oscillators. The frequency of a
mass-spring system is explicitely dependent on the mass.
Wednesday, September 14, 2005: Solution for Quiz 3
Friday, September 09, 2005: Solution for Quiz 2
Friday, September 02, 2005: solution for Quiz 1. If you
have no calculator with you, please write down the procedure or equation with
numbers you would follow. Bring your calculator to class.
Some of you
answered “pitch” as a difference for note C played on organ and harp. Note C is
a descriptor for pitch. If both instruments play the same note, they play in
the same pitch (ideally). Differences are timbre, loudness and duration.
Page last
modified: 11/17/2005 2:11 PM
Maintained
by Sylke Boyd, sboyd@umn.edu
University
of Minnesota-Morris, Division of Science and Mathematics