#$&*
PHY 121
Your 'cq_1_05.1' report has been received. Scroll down through the document to see any comments I might have inserted, and my final comment at the end.
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September 18, 2011 at 1:33 a.m.
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15 min.
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The problem:
A ball accelerates at 8 cm/s^2 for 3 seconds, starting with velocity 12 cm/s.
• What will be its velocity after the 3 seconds has elapsed?
answer/question/discussion: ->->->->->->->->->->->-> :
12 cm/s + 8 cm/s (1 sec) + 8 cm/s (2 sec) + 8 cm/s (3 sec) = 28 cm/s
@& Good thinking, but 12 + 8 + 8 + 8 = 36, not 28.*@
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• Assuming that acceleration is constant, what will be its average velocity during this interval?
answer/question/discussion: ->->->->->->->->->->->-> :
`ds = 12 + 20 + 28 = 60
vAve = 60 cm (`ds) / 3 s (`dt) = 20 cm/s
@& The ball moves more than 12 cm during the first second, because it starts out at 12 cm/s and speeds up.
It moves more that 28 cm during the last second. During that third second it is never moving as slowly as 28 cm/s, which is its average velocity and is attained between t = 1 sec and t = 2 sec.
*@
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• How far will it travel during this interval?
answer/question/discussion: ->->->->->->->->->->->-> :
`ds = (vf - v0) = 60 cm
#$&*
&#See any notes I might have inserted into your document, and before looking at the link below see if you can modify your solutions. If there are no notes, this does not mean that your solution is completely correct.
Then please compare your old and new solutions with the expanded discussion at the link
Solution
Self-critique your solutions, if this is necessary, according to the usual criteria. Insert any revisions, questions, etc. into a copy of this posted document. Mark any insertions with &&&& so they can be easily identified.If your solution is completely consistent with the given solution, you need do nothing further with this problem. &#
#$&*
PHY 121
Your 'cq_1_05.1' report has been received. Scroll down through the document to see any comments I might have inserted, and my final comment at the end.
** **
________________________________________
The problem:
A ball accelerates at 8 cm/s^2 for 3 seconds, starting with velocity 12 cm/s.
• What will be its velocity after the 3 seconds has elapsed?
answer/question/discussion: ->->->->->->->->->->->-> :
12 cm/s + 8 cm/s (1 sec) + 8 cm/s (2 sec) + 8 cm/s (3 sec) = 36 cm/s
#$&*
• Assuming that acceleration is constant, what will be its average velocity during this interval?
answer/question/discussion: ->->->->->->->->->->->-> :
vAve = (12 cm/s + 36 cm/s) / 2 = 24 cm/s
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• How far will it travel during this interval?
answer/question/discussion: ->->->->->->->->->->->-> :
1st second 12 cm + 2nd second 20 cm + 3rd second 28 cm = 60 cm
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@& The ball starts the first second at 12 cm/s and speeds up. It goes further than 12 cm during that second.
There is a similar flaw in your reasoning on each of the quantities you have added.
However you're on the right track.*@
@&
&#See any notes I might have inserted into your document, and before looking at the link below see if you can modify your solutions. If there are no notes, this does not mean that your solution is completely correct.
Then please compare your old and new solutions with the expanded discussion at the link
Solution
Self-critique your solutions, if this is necessary, according to the usual criteria. Insert any revisions, questions, etc. into a copy of this posted document. Mark any insertions with &&&& so they can be easily identified.If your solution is completely consistent with the given solution, you need do nothing further with this problem. &#
*@