Time and Date Stamps (logged): 01:52:06 08-29-2008
¯°Ÿ´±Ÿ¯µ¯·Ÿ±¸Ÿ±¯¯·
Precalculus II
Principles of Physics (Phy 121) Test_2
Completely document your work and your reasoning.
You will be graded on your documentation, your reasoning, and the
correctness of your conclusions.
Test should be printed using Internet Explorer. If
printed from different browser check to be sure test items have not been cut off. If
items are cut off then print in Landscape Mode (choose File, Print, click on Properties
and check the box next to Landscape, etc.).
Name and Signature of Student
_____________________________
Signed by Attendant, with Current Date and Time:
______________________
If picture ID has been matched with student and name as
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:
. . . . .
. . . .
. . . .
. . .
.
.
.
.
.
.
.
.
.
.
Problem Number 1
How much paint is applied per square meter
if 4 gallons of paint are uniformly spread out over the surface of a sphere of radius 8.1
meters?
- If the paint is applied over a sphere of double
the radius, by what factor does the amount per square meter change?
- If the paint is applied over a sphere of four
times the radius, by what factor does the amount per square meter change?
If the paint is applied over a sphere of radius
7 meters, what is the factor by which the amount per square meter changes?
.
.
.
.
.
.
.
.
.
.
Problem Number 2
An object is moving on a circle whose radius is
8 meters.
- At what rate, in radians/second, is the angle of
the radial line from the center of the circle to the object changing if the object
completes 81 revolutions per second?
- How fast is the object therefore moving?
.
.
.
.
.
.
.
.
.
.
Problem Number 3
A small object orbits a planet at a distance
of 20000 kilometers from the center of the planet with a period of 69 minutes. What is the
mass of the planet?
.
.
.
.
.
.
.
.
.
.
Problem Number 4
Give the strength of the gravitational attraction
felt by a human being of mass 90 kg to a spherical object with radius 2 km and uniform
density 3 times that of water (water's density is 1000 kg/m ^ 2), assuming that the
person's entire mass is located at the surface of the sphere. You may use G =
6.67 * 10^-11 N m^2 / kg^2.
Give the attraction if the sphere was compressed to
a radius of 200 meters, and if it was compressed to radius 20 meters.
To what radius would the sphere have to be
compressed in order to exert a force equal to the weight of this individual on the surface
of the Earth?
.
.
.
.
.
.
.
.
.
.
Problem Number 5
A massless disk is constrained to rotate about an
axis through its center and perpendicular to its plane. Iron rods are shaped into circles
whose radii are 2.399 meters, 4.798 meters and 7.197 meters. These circles are secured to the disk,
concentric with it. The rods have mass density 1.526611 kilograms/meter.
- Find the angular acceleration that will result from
the application of a torque of 1555 meter Newtons.
.
.
.
.
.
.
.
.
.
.
Problem Number 6
What angular acceleration results when a net torque
of 1617 meter Newtons is applied to the system described below?
The system consists of a massless disk is
constrained to rotate about an axis through its center and perpendicular to its plane.
- Circles concentric with the disk are drawn on the
disk, the first having radius 9.399 meters, the second twice and the third three times that
radius.
- Around each circle, masses of 9 kilograms are
evenly distributed, with 2.349 / `pi meters of arc between masses.
.
.
.
.
.
.
.
.
.
.
Problem Number 7
A person of mass 68 kg begins climbing a very high tower. The tower begins at the
surface of the Earth, at a distance of 6400 km from the center, and rises to a position 3300
kilometers further from the center.
- For each of the first three 1100 kilometer segments, determine the average
of the initial and final gravitational forces encountered while climbing the segment.
- Give the total work required for each segment, based on the average of
the initial and final forces for the segment.
- At an average power output of 1.03 watt/kg for 8 hours per day, how many
days would be required to make the 3300 kilometer climb?
.
.
.
.
.
.
.
.
.
.
Problem Number 8
A turbine accelerates uniformly at 1
radians/second/second.
- How long will it a to accelerate from .8
radians/second to 3.3 radians/second?
- Through what angular displacement will it turn in
this time?