cq_1_061

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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: ->->->->->->->->->->->-> :

 

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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: ->->->->->->->->->->->-> :

 vf=v0+a*dt

50=v0+10*3=

50=v0+30

v0=20cm/s

ds=(v0+vf)/2*dt

ds=(20+50)/2*3

ds=35*3

ds=105cm

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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: ->->->->->->->->->->->-> :

 Good thing this is the seed, because everything will be a guess.

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Then for each situation answer the following:

• Is it possible from this information to directly determine vAve? 

answer/question/discussion: ->->->->->->->->->->->-> :

 At the end of the first sec., the ball will travel 20cm, at the end of the sec., the ball will have traveled 60cm. I think it will take 1.25 sec. to travel the 30cm at 20cm/s^2.

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At the end of the first second the ball will be traveling at 20 cm/s. However it doesn't travel at that speed for the entire first second. As it turns out it travels only 10 cm during the first second.

At the end of another second it will be moving at 40 cm/s, and will have traveled an additional 30 cm.

It therefore takes over 2 sec to travel the 30 cm.

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• Is it possible to directly determine `dv? 

answer/question/discussion: ->->->->->->->->->->->-> :

If i’m right about the previous question than 1.25sec*20cm/s^2=25cm/s

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http://vhcc2.vhcc.edu/dsmith/forms/common_questions/ph1_cq_I_06_1.htm

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20

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The question asked you to identify the given quantities for three different situations. You didn't read the question right, but you clearly know how to do this so we won't worry about that part.

You did solve two problems. Your reasoning on the first was correct, but that isn't the case on the second, so be sure to see my notes.

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