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Phy 201
Your 'cq_1_01.1' 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_01.1_labelMessages **
The problem:
Here is the definition of rate of change of one quantity with respect to another:
The average rate of change of A with respect to B on an interval is
• average rate of change of A with respect to B = (change in A) / (change in B)
Apply the above definition of average rate of change of A with respect to B to each of the following. Be sure to identify the quantity A, thequantity B and the requested average rate.
• If the position of a ball rolling along a track changes from 10 cm to 20 cm while the clock time changes from 4 seconds to 9 seconds, what is the average rate of change of its position with respect to clock time during this interval?
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
the change in A is 20 cm from 10cm = 10cm
the change in B is 4 s to 9 s= 5 s
A/B= 10cm/ 5s
= 2cm/s is the average rate
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• If the velocity of a ball rolling along a track changes from 10 cm / second to 40 cm / second during an interval during which the clock time changes by 3 seconds, then what is the average rate of change of its velocity with respect to clock time during this interval?
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
10cm/ s to 40cm/s is A = 30cm/s
B= 3seconds
A/B= 30/ 3= 10cm/s
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30 / 10 is a meaningless calculation.
30 dollars / (10 hours) would be meaningful.
30 cm / (10 sec) would be meaningful.
30 cm/s / (10 s) would be meaningful.
Units must be included with every quantity that has units, at every step of every calculation.
This helps focus on the meaning of the calculation, and also provides a check. If the units at the end of the calculation don't match the units of the quantity being calculated, this reveals an error in either the algebra of the units calculation, or in the analysis of the problem itself.
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The units at the end of your calculation do not match the units that would result from a correct calculation. See if you can correct this.
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• If the average rate at which position changes with respect to clock time is 5 cm / second, and if the clock time changes by 10 seconds, by how much does the position change?
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
average rate is 5cm/ s
B is 10 seconds
5cm/s * 10 s = 50cm = A
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• You will be expected hereafter to know and apply, in a variety of contexts, the definition given in this question. You need to know this definition word for word. If you try to apply the definition without using all the words it is going to cost you time and it will very likely diminish your performance. Briefly explain how you will ensure that you remember this definition.
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
I will try to use this definition when thinking through problems. I have written down the definition in my notes, and will refer to it when it is needed for problems.
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• You are asked in this exercise to apply the definition, and given a general procedure for doing so. Briefly outline the procedure for applying this definition, and briefly explain how you will remember to apply this procedure.
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
when trying to apply the definition I read through the problem and see what will give the average rate of change, and label each change as A or B. If the average rate of change is already given I decide which element is missing, change in A or change in B. I will remember by slowly thinking through the procedure of solving the problem.
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Your approach is very good. However you made an error with units, and we want to get that straight at the very beginning.
&#Please see my notes and submit a copy of this document with revisions, comments and/or questions, and mark your insertions with &&&& (please mark each insertion at the beginning and at the end).
Be sure to include the entire document, including my notes. &#
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