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Physics II
Principles of Physics (Phy 122) Test_Set_6
Completely document your work and your reasoning.
You will be graded on your documentation, your reasoning, and the
correctness of your conclusions.
** Write clearly in dark pencil or ink, on one side of the paper
only. **
10-02-2001 16:06:59
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and check the box next to Landscape, etc.).
Name and Signature of Student
_____________________________
Signed by Attendant, with Current Date and Time:
______________________
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given above, Attendant please sign here: _________
Instructions:
- Test is to be taken without reference to text or
outside notes.
- Graphing Calculator is allowed, as is blank paper or
testing center paper.
- No time limit but test is to be taken in one
sitting.
- Please place completed test in Dave Smith's folder,
OR mail to Dave Smith, Science and Engineering, Va. Highlands CC, Abingdon, Va.,
24212-0828 OR email copy of document to dsmith@vhcc.edu,
OR fax to 276-739-2590. Test must be returned by individual or agency supervising test. Test is not to be returned to student after it has been taken. Student may, if proctor deems it feasible, make and retain a copy of the test..
Directions for Student:
- Completely document your work.
- Numerical answers should be correct to 3 significant
figures. You may round off given numerical information to a precision consistent
with this standard.
- Undocumented and unjustified answers may be counted
wrong, and in the case of two-choice or limited-choice answers (e.g., true-false or
yes-no) will be counted wrong. Undocumented and unjustified answers, if wrong, never get
partial credit. So show your work and explain your reasoning.
- Due to a scanner malfunction and other errors some
test items may be hard to read, incomplete or even illegible. If this is judged by
the instructor to be the case you will not be penalized for these items, but if you
complete them and if they help your grade they will be counted. Therefore it is to
your advantage to attempt to complete them, if necessary sensibly filling in any
questionable parts.
- Please write on one side of paper only, and staple
test pages together.
Test Problems:
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Constants
Constants:
| k = 9*10^9 N m^2 / C^2 |
qE = 1.6 * 10^-19 C |
h = 6.63 * 10^-34 J s |
| energy of n=1 orbital in hydrogen atom: -13.6 eV |
k ' = 9 * 10^-7 T m / amp |
atomic mass unit: 1.66 * 10^-27 kg |
| electron mass: 9.11 * 10^-31 kg |
speed of light: 3 * 10^8 m/s |
Avogadro's Number: 6.023 * 10^-23 particles/mole |
| Gas Constant: R = 8.31 J / (mole K) |
proton mass: 1.6726 * 10^-27 kg |
neutron mass: 1.6749 * 10^-27 kg |
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Problem Number 1
A wave is traveling at 90 meters/second and has
frequency 45 cycles/sec. What is the wavelength of the wave?
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Problem Number 2
If a wave with 2 meters between peaks
passes at the velocity of 22 meters/second, then how many peaks pass in a second?
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Problem Number 3
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Problem Number 4
A simple harmonic oscillator drives the ends of two strings, identical except for a
length difference of 2 cm, at frequency 168.7 Hz, then at 96.43 Hz, then at 120.5 Hz and finally
at 144.6 Hz at an amplitude of .3 cm.
The strings are under identical tensions and are positioned with their far ends
attached to the nose ring of a volunteer. The strings have mass density 19.7 grams/meter and
are each under a tension of 3.8 Newtons (not quite enough hurt).
Which of the frequencies will be most likely to cause the volunteer more discomfort
than the others, and which the least?
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Problem Number 5
A sound source is moving toward a microphone at 37 m/s, emitting sound at a
constant frequency of 480 Hz (i.e., 480 pulses per second).
If the source starts out 10 meters from the microphone, then
- How many pulses are emitted as the source approaches the microphone?
- How long is it between the instant the microphone receives the first pulse and
the last?
- What sound frequency is therefore received by the microphone?
You may assume that sound travels at about 340 m/s.
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Problem Number 6
What are the frequencies of the first four
harmonics of a hole bored into the side of a hill, 8 meters long with its opening
clear? Assume that sound travels in the air inside at 330 m/s.
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Problem Number 7
Suppose that you are holding one end of a Slinky
and the other end is attached to a wall. The Slinky is held at some constant tension. If
you tweak the Slinky by displacing some coils perpendicular to a direction parallel to the
direction in which waves propagate through it, the disturbance requires .6
seconds to travel its length. You want to create a standing wave in the Slinky by moving
your end in a low-amplitude simple harmonic motion perpendicular to the direction of wave
propagation (the SHM has a small enough amplitude that you can regard your end, for
practical purposes, as a node).
As you answer the following, give a full
description of what happens and why, as well as a correct mathematical analysis.
- If you wish to create a wave with nodes at its two
ends and only one antinode, then what must be the frequency and period of the SHM with
which you drive the wave?
- What would be the frequency of your SHM if the wave,
with nodes at both ends, contained exactly two antinodes?
- What if the number of antinodes was three?
- What if the number of antinodes was four?
- What is the wavelength of each mode of vibration, in
terms of the length of the Slinky (e.g., 1/3 of the length, 5 times the length, etc.)?
- What is the ratio sequence corresponding to the
sequence of frequencies?
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Problem Number 8
#8: Extra Credit for Physics 122 or Physics 112 (required of others)
**This problem is required of General
College Physics and University Physics students only.**
A twelve-centimeter length of string is deformed so
that the displacements from equilibrium at 3-cm intervals along the string are -.03001 , -.1301 ,
-.02001, .16 and .02 centimeters.
As an approximation, assume that all the mass
within 1.5 cm on either side of each measured point is concentrated in the form of a bead
at the measured point.
Answer the following:
- If each 1-cm segment of the string has a mass of
1.5 grams, and if the string is under a tension of 190 Newtons, then what
are the accelerations of each of the three middle beads defined by the information given
above?
- Explain how we could calculate the approximate new
position of each bead after a short time interval, given the velocity of each bead.
- How would the accelerations change if the string
tension was doubled, if the masses of the segments were doubled, and if the tension was
doubled while the masses were halved?
#8: Extra Credit for Physics 122 or Physics 112 (required of others)
#8: Extra Credit for Physics 122 or Physics 112 (required of others)
#8: Extra Credit for Physics 122 or Physics 112 (required of others)