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Phy 201
Your 'cq_1_06.1' 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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For each situation state which of the five quantities v0, vf, `ds, `dt and a are given, and give the value of each.
• A ball accelerates uniformly from 10 cm/s to 20 cm/s while traveling 45 cm.
answer/question/discussion: ->->->->->->->->->->->-> :
v0= 10 cm/s
vf= 20 cm/s
‘ds= 45 cm
vAve= (vf+v0)/2
vAve= 20 cm/s + 10 cm/s / 2
vAve = 30 cm/s / 2 = 15 cm/s
dt= ds/ vAve
dt= 45 cm/ 15 cm/s
dt= 3 s
a= (vf-v0)/’dt
a= (20 cm/s - 10 cm/s) / 3s
a= 3.33 cm/s^2
Yes, it is possible to determine the vAve.
Yes, it is possible to determine the dv.
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• A ball accelerates uniformly at 10 cm/s^2 for 3 seconds, and at the end of this interval is moving at 50 cm/s.
answer/question/discussion: ->->->->->->->->->->->-> :
a= 10 cm/s^2
‘dt= 3 s
vf= 50 cm/s
Dv= aAve * dt
Dv= 10 cm/s^2 * 3 s
Dv= 30 cm/s
V0= vf- dv
V0= 50 cm/s - 30 cm/s
V0= 20 cm/s
Ds= v0*dt+.5a*dt
Ds= 20 cm/s* 3s + .5(10 cm/s2)* 3 s
Ds= 75 cm
Yes, it is possible, once you find the dv, to determine the vAve with this information.
Yes, it is possible to determine the dv.
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• A ball travels 30 cm along an incline, starting from rest, while accelerating at 20 cm/s^2.
answer/question/discussion: ->->->->->->->->->->->-> :
ds= 30 cm
a= 20 cm/s^2
v0=0
I don’t know how to answer this question and I have spent a good deal of time one it. Is the starting time 0 because it starts at rest? How do you find the change in time?
@& The starting time isn't given so it can be anything you want to make it.
The analysis doesn't involve a starting time, only the change in clock time for the interval you are considering.
For this interval you know v0, a and `ds.
To solve this problem you need to list the four equations of motion, and locate the equation(s) that include v0, a and `ds. All four equation contain four quantities, so any equation that contains three quantities can be solved for a fourth.
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No, it is not possible to directly find the vAve with this information.
No, it is not possible to directly find the dv with this information.
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Then for each situation answer the following:
• Is it possible from this information to directly determine vAve?
answer/question/discussion: ->->->->->->->->->->->-> :
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• Is it possible to directly determine `dv?
answer/question/discussion: ->->->->->->->->->->->-> :
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40 min
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6/24 11:00 pm
self-critique #$&*
#$&* self-critique
self-critique rating
rating #$&*:
&#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. &#
@& You did very well with identifying the quantities.
The question didn't actually ask for a complete solution, but you did give excellent solutions for the first two situations.
For the third situation there is no way to find vAve or `dv, so you would need to do as indicated in my note, using the four equations of uniformly accelerated motion.*@