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Phy 121
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, 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):
The question asks for the rate of change in position with respect to change in time. Therefore, rate of change in position will be ‘A’. Change in time will be ‘B’.
Ave rate of change of A with respect to B=(change in A)/(change in B)=(‘ds)/(‘dt)=(20cm-10cm)/(9s-4s)=(10cm)/(5s)=2cm/s. As the ball travels the distance of 10cm, the elapsed time is 5 seconds. So, at 2cm/s after 5 seconds the ball will have traveled 10cm. It all checks. The average rate of change with respect to time is 2cm/s.
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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):
Following the question ‘with respect to clock time during this interval’. Quantity B will be the 3 second time interval. Quantity A will be the 10cm/s to 40cm/s change.
Average rate of change of A with respect to B=(delta A)/(delta B)=(‘ds)/(‘dt)=(40cm/s-10cm/s)/(3s)=(30cm/s)/(3s)=10cm/s
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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):
The average rate of change of A with respect to B=(delta A)/(delta B)
Let A = unknown ,Let B = clock delta time 10s, Let (delta A)/(delta B)=5cm/s
Solving fo delta A=(delta B)*(5cm/s)=(10s)*(5cm/s)=50cm
Delta A=50cm
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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):
To start I typed the definition in all my answers above. I will add it to my written class notes formula sheet.
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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):
Before applying the definition of’the average rate of change of A with respect to B on an interval=(delta A)/(delta B)', I will identify quantity A, quantity B and/or (deltaA)/(deltaB).
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Your work looks very good. Let me know if you have any questions.