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Phys201
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 **
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, the quantity 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):
9 sec -4 sec=5sec
20cm-10cm=10cm
10cm (A)/5 sec(B)=2 sec is avg rate of change
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10 cm / (5 sec) = (10 / 5) (cm / sec) = 2 cm / sec, not 2 sec.
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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):
40-10=30 sec
30 sec (A)/3 sec (B)=10 sec avg rate of change
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40 - 10 = 30, not 30 sec.
40 sec - 10 sec = 30 sec.
However 40 sec and 10 sec are not part of the information for this problem.
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If you did have 30 sec / (3 sec) the result would be 10 sec / sec = 10, since the seconds would divide out. However since the numerator doesn't have units of seconds, this is not relevant to this solution.
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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):
10 secs (A)/5 cm/sec(B)=2 cm per sec
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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):
The average rate of change is =(change in A)/ (change in B) I will remember this definition because I have not only memorized it but have put it to use in this exercise. The more you are able to use a definition the easier it is to recall the definition.
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You appear to be using the definition correctly, but you are not using units correctly, which tends to hamper your understanding of what you are doing as you solve the problem.
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