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Phy 121
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.
** CQ_1_09.1_labelMessages **
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=20cm
v0=0
dt=2sec
vave=20cm/2sec= 10cm/sec
vf=2vAve=20cm/sec
a='dv/'dt = 20cm/sec/2sec = 10cm/sec^2
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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: ->->->->->->->->->->->-> :
'dt=2*1.03=2.06sec
vAve=20cm/2.06sec=9.709cm/sec
vf=2vAve = 19.417cm/sec
a='dv/'dt = 19.417cm/sec/2.06sec = 9.426cm/sec^2
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• What is the percent error in each?
answer/question/discussion: ->->->->->->->->->->->-> :
acceleration error= (10-9.426)/10 *100=5.74%
velocity error = (10-9.709)/10*100=2.91%
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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: ->->->->->->->->->->->-> :
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• If the percent errors are different explain why it must be so.
answer/question/discussion: ->->->->->->->->->->->-> :
When I found velocity the time interval used had 3% error. When I calculated the acceleration, the time interval now introduced an additional 3% error so the total error was 6% error. This should explain why the percent errors are different.
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&#Very good responses. Let me know if you have questions. &#