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PHY 241
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: ->->->->->->->->->->->-> :
vf=?
v0=0
'dt=2
`ds=20cm
a=?
vave= `ds/`dt
vave= 20cm/2s=10cm/s
vave=vf+vo/2
10cm/s=vf+0/2
Vf=20cm/s
20cm/s = 0 + a * 2
A=10cm/s^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: ->->->->->->->->->->->-> :
2s-3%=1.94s
vave= `ds/`dt
vave= 20cm/1.94s=10.31cm/s
vave=vf+vo/2
10.31cm/s=vf+0/2
Vf=20.62cm/s
20cm/s = 0 + a * 1.94
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The 3% error in the time has already changed the final velocity. You wouldn't apply the final velocity from the earlier calculation to the present calculation.
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A=10.31cm/s^2
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• What is the percent error in each?
answer/question/discussion: ->->->->->->->->->->->-> :
10/10.31=97%accurate = 3% error on both
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You'll need to correct your calculation of acceleration before correcting this.
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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: ->->->->->->->->->->->-> :
the error is only in time therefore there is 3 percent error in all numbers. In other words there is no compounding error. So all numbers we get from this data will be 3 percent error.
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• If the percent errors are different explain why it must be so.
answer/question/discussion: ->->->->->->->->->->->-> :
They are not different.
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*#&!
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The percent errors are in fact different.
You'll be able to correct this easily.
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