Phy 231
Your 'cq_1_09.1' report has been received. Scroll down through the document to see any comments I might have inserted, and my final comment at the end.
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A ball accelerates uniformly as it rolls 20 cm down a ramp, starting from rest, in 2 seconds.
• What are its average velocity, final velocity and acceleration?
answer/question/discussion: ->->->->->->->->->->->-> :
ds = 20 cm
v0 = 0 cm/s
dt = 2 sec
20 cm/2sec = 10 cm/s = vAve
vAve = 10 cm/s
10 cm/s = (vf+0cm/s)/2
vf = 20 cm/s
a = 20 cm/s/2sec = 10 cm/s/s
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• If the time interval is in error so that it is 3% longer than the actual time interval, then what are the actual values of the final velocity and acceleration?
answer/question/discussion: ->->->->->->->->->->->-> :
2 * 0.3 = 0.06
2 + 0.06 = 2.06
dt = 2.06 sec
10 cm/s = (vf + 0 cm/s) / 2.06
vf = 20.6 cm/sec
If the time interval is 2.06 seconds, then the average velocity will no longer be 10 cm/s.
20 cm/s / 2.06 sec = 9.71 cm/s/s or 20.6 cm/s / 2.06 sec = 10 cm/sec
I was unaware whether or not I was supposed to use the original velocity or the one that was found by using the 3% error.
If the actual interval differs from the original interval as stated, then you would use the actual interval in your calculations.
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• What is the percent error in each?
answer/question/discussion: ->->->->->->->->->->->-> :
3% in the time interval 3% in velocity and 3% in acceleration
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• If the percent error is the same for both velocity and acceleration, explain why this must be so.
answer/question/discussion: ->->->->->->->->->->->-> :
This must be so because the percent error in one will stay the same all throughout because they are proportional. If you start off with 3% error in something, it will stay that way the entire way through.
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• If the percent errors are different explain why it must be so.
answer/question/discussion: ->->->->->->->->->->->-> :
Different percent errors may be because the acceleration is not in a uniform motion which will give values that are not proportional or similar to each other. Equations may have been calculated wrong or there may have been other human errors which affected the calculations also.
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15 mins
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&#Please compare your solutions with the expanded discussion at the link
Solution
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