Time and Date Stamps (logged): 17:12:20 06-10-2020
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Precalculus II
University Physics (Phy 231, Phy 241) Test 1
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:
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Problem Number 1
How well does the following data set support the hypothesis that a graph
of average acceleration vs. slope will be linear?
- A straight ramp 65 cm long is inclined at various slopes.
- The time required for a cart to coast 65 cm down the ramp, starting from
rest, is 2.674613 seconds on the first incline, 2.989937 seconds on the next, and 1.936697 seconds on
the last.
- The differences in elevation between one end and the other, for the
different slopes, are 1.9, 4.2 and 6.7 cm.
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Problem Number 2
The acceleration of an object is constant at a m/s^2. If the
velocity at t = 0 is v0 and the position at t = 0 is x0, then in terms of these symbols
what are the corresponding velocity and position functions?
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Problem Number 3
A cart of mass .6 kg coasts 55 cm up an incline at 7 degrees with horizontal.
Assume that frictional and other nongravitational forces parallel to the incline
are negligible.
- What is the component of the cart's weight parallel to the incline?
- How much work does this force do as the cart rolls up the incline?
- How much work does the net force do as the cart rolls up the incline?
- Using the definition of kinetic energy determine the velocity of the cart after
coasting the 55 cm, assuming its initial velocity to be zero.
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Problem Number 4
An Atwood machine consists of masses of 1 kg and 1.17 kg on opposite sides of a light
frictionless pulley. The system is given an initial velocity of .59 m/s in the direction of
the 1 kg mass.
- How much work does gravity do on the system between the initial instant and the instant
at which the system comes to rest, and how much work is done by the system against gravity
during this time?
- How far does the system therefore travel during this time (solve using energy
considerations)?
- How are the work done by the system and its kinetic energy change related?
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Problem Number 5
Reason out the quantities v0, vf, Dv,
vAve, a, Ds and Dt:
If an object’s initial velocity is 10 cm/s, and it accelerates uniformly through 80.5
cm in 7 seconds, then what is its acceleration?
Using the equations which govern uniformly accelerated motion determine vf, v0, a, Ds and Dt for an object
which accelerates at .428 cm/s/s through a distance of 80.5 cm, ending with velocity 10
cm/s.
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Problem Number 6
Discuss the forces acting on a dynamics cart with negligible friction as it coasts down
an incline.
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Problem Number 7
A system consists of a cart pulled along a constant-velocity ramp by the force of
gravity on a single paper clip, whose mass is much less than that of the cart, attached by
a thread over a pulley with negligible friction. If the system accelerates at 3.8 cm/s2,
and if F = m a describes the relationship among net force F, mass m and acceleration a,
give the acceleration of each of the following:
The same system but with 9 paper clips instead of one.
The same system but with a single paper clip and a cart of twice the mass.
The same system but with a single paper clip with a cart of half the mass.
The same system but with 11 paper clips and a cart of 17 times the mass.
What would be the acceleration of the same system but with a number of paper clips
whose mass equals that of cart?
How would the slope of a graph of acceleration vs. number of paper clips for the
original system (for a small number of paper clips) compare with the slope for a system
with double the cart mass, and how would it compare with the slope of a system with 11
times the cart mass?
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Problem Number 8
The force exerted by a certain rubber band at stretch x is given by the function
F(x) = k x^ .68, with k = 130 N / m^ .68.
- When a mass of .5 kg, intially at rest, is accelerated by the rubber band at a
stretch of x = .198 meters, what will be the velocity of the object when the rubber band
goes slack (assume that none of the potential energy in the rubber band is dissipated and
that the mass of the rubber band is negligible)?
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Problem Number 9
When masses of 65, 130 and 195 grams are hung from a certain rubber band its
respective lengths are observed to be 38, 48 and 58 cm. What are the x and y components of
the tension of a rubber band of length 46.3 cm if the x component of its length if 35.70869 cm?
What vertical force, when added to this force, will result in a total
force of magnitude 300 grams (a gram force is the force of gravity on a one gram mass)?