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PHY201
Your 'cq_1_22.2' report has been received. Scroll down through the document to see any comments I might have inserted, and my final comment at the end.
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A 70 gram ball rolls off the edge of a table and falls freely to the floor 122 cm below. While in free fall it moves 40 cm in the horizontal direction. At the instant it leaves the edge it is moving only in the horizontal direction. In the vertical direction, at this instant it is moving neither up nor down so its vertical velocity is zero. For the interval of free fall:
What are its final velocity in the vertical direction and its average velocity in the horizontal direction?
answer/question/discussion: ->->->->->->->->->->->-> :
vf^2=2*9.8*.04
,h3>40 cm is .4 m, not .04 m
However that's horizontal displacement, while 9.8 m/s^2 is vertical acceleration. The two don't belong together.
vf=.88m/s
vAve=.88/2= .44
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Assuming zero acceleration in the horizontal direction, what are the vertical and horizontal components of its velocity the instant before striking the floor?
answer/question/discussion: ->->->->->->->->->->->-> :
arctan (122/40)= 71.8
That would be the angle below horizontal from the edge of the table to the striking point on the floor. However the ball doesn't move on a straight-line path, so that's not the direction of its motion.
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What are its speed and direction of motion at this instant?
answer/question/discussion: ->->->->->->->->->->->-> :
.718*.44=.3159m/s
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What is its kinetic energy at this instant?
answer/question/discussion: ->->->->->->->->->->->-> :
.5(9.8)^2(70)=3.361N
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What was its kinetic energy as it left the tabletop?
answer/question/discussion: ->->->->->->->->->->->-> :
should be the same
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What is the change in its gravitational potential energy from the tabletop to the floor?
answer/question/discussion: ->->->->->->->->->->->-> :
.5(3.361)(.44)^2=.32
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How are the the initial KE, the final KE and the change in PE related?
answer/question/discussion: ->->->->->->->->->->->-> :
KE get greater the PE gets smaller
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How much of the final KE is in the horizontal direction and how much in the vertical?
answer/question/discussion: ->->->->->->->->->->->-> :
Don't know
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30 minutes
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I didn't get the last one or probably any of it right.
You were on the right track but missed a number of details. You should submit a revision on this one.
&#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. &#
&#Good work. Let me know if you have questions. &#
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