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Phy 201
Your 'cq_1_00.1' report has been received. Scroll down through the document to see any comments I might have inserted, and my final comment at the end.
** CQ_1_00.1_labelMessages **
• Pick one of the videos, and write down the position and clock time of one of the objects, as best you can determine them, in each of three different frames. The three frames should all depict the same 'roll' down the ramp, i.e. the same video clip, at three different clock times. They should not include information from two or more different video clips.
• For each of the three readings, simply write down the clock time as it appears on the computer screen, and the position of the object along the meter stick. You can choose either object (i.e., either the pendulum or the roll of tape), but use the same object for all three measurements. Do not go to a lot of trouble to estimate the position with great accuracy. Just make the best estimates you can in a couple of minutes.
Which object did you choose and what were the three positions and the three clock times?
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
I chose the roll of tape in the first video.
Clock Time 1: 59.39, Position: 4 inches
Clock Time 2: 59.796, Position: 14 inches
Clock time 3: 60.015, Position: 22 inches
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In the following you don't have to actually do calculations with your actual data. Simply explain how you would use data of this nature if you had a series of several position vs. clock time observations:
• If you did use observations of positions and clock times from this video, how accurately do you think you could determine the positions, and how accurately do you think you would know the clock times? Give a reasonable numerical answer to this question (e.g., positions within 1 meter, within 2 centimeters, within 3 inches, etc; clock times within 3 seconds, or within .002 seconds, or within .4 seconds, etc.). You should include an explanations of the basis for your estimate: Why did you make the estimate you did?
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
I feel like my determination of the positions wasn’t as accurate as it could’ve been just due to estimating on the ruler from a distance. I’d say that I could get the predictions accurate within 3 inches. I think the clock times were very accurate given the decimal places included in each measurement when I stopped the clock (within .002 seconds).
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• How can you use observations of position and clock time to determine whether the tape rolling along an incline is speeding up or slowing down?
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
You can compare the amount of space moved from one second to the next at multiple time points and see if the amount of space moved is increasing or decreasing. If the amount of space moved per second is increasing, then it is speeding up.
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• How can you use observations of position and clock time to determine whether the swinging pendulum is speeding up or slowing down?
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
You can count the time it takes the pendulum to make one cycle and then count the time it takes to make the next cycle. If the time decreases between the two counts, the pendulum is speeding up. If it increases, it is slowing down.
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• Challenge (University Physics students should attempt answer Challenge questions; Principles of Physics and General College Physics may do so but it is optional for these students): It is obvious that a pendulum swinging back and forth speeds up at times, and slows down at times. How could you determine, by measuring positions and clock times, at what location a swinging pendulum starts slowing down?
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
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• Challenge (University Physics students should attempt answer Challenge questions; Principles of Physics and General College Physics may do so but it is optional for these students): How could you use your observations to determine whether the rate at which the tape is speeding up is constant, increasing or decreasing?
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
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&#Good work. Let me know if you have questions. &#
PHY 241
Your 'cq_1_07.2' report has been received. Scroll down through the document to see any comments I might have inserted, and my final comment at the end.
** CQ_1_07.2_labelMessages **
An automobile rolls 10 meters down a constant incline with slope .05 in 8 seconds, starting from rest. The same automobile requires 5 seconds to roll the same distance down an incline with slope .10, again starting from rest.
• At what average rate is the automobile's acceleration changing with respect to the slope of the incline?
answer/question/discussion: ->->->->->->->->->->->-> :
vf=?
v0=0
'dt=8s
`ds=10m
a=?
slope of .05 - find acceleration first by finding vf
10m = (0 + vf) / 2 * 8s
Vf=2.5m/s
vf = v0 + a * `dt
2.5m/s = 0 + a * 8s
A=0.3125 m/s^2
vf=?
v0=0
'dt=5s
`ds=10m
a=?
slope of .10 - find acceleration first by finding vf
10m = (0 + vf) / 2 * 5s
Vf=4m/s
vf = v0 + a * `dt
4m/s = 0 + a * 5s
A=.8 m/s^2
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Your accelerations are correct.
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I think at this point I should find the slope between the two points
Acceleration vs time slope
8s-5s/.8-.3125= 3s/.4875=6.15m/s^2 for every 1slope
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You didn't include units in this calculation, which also needs to include grouping:
(8s-5s)/(.8 m/s^2-.3125 m/s^2).
What are the correct units of this calculation? They are not m/s^2, and no slope units are involved.
With the right units your calculation would indicate the rate of change of clock time with respect to acceleration. However this is not the rate that was requested. Go back to the definition of average rate and be sure you are applying it correctly to the given questions.
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*#&!`gr99
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