#$&*
Phy 121
Your 'cq_1_01.1' report has been received. Scroll down through the document to see any comments I might have inserted, and my final comment at the end.
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The problem:
Here is the definition of rate of change of one quantity with respect to another:
The average rate of change of A with respect to B on an interval is
• average rate of change of A with respect to B = (change in A) / (change in B)
Apply the above definition of average rate of change of A with respect to B to each of the following. Be sure to identify the quantity A, the quantity B and the requested average rate.
• If the position of a ball rolling along a track changes from 10 cm to 20 cm while the clock time changes from 4 seconds to 9 seconds, what is the average rate of change of its position with respect to clock time during this interval?
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
#$&* Average Rate of Change: 20-10/9-4=10/5= 2 seconds.
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You are using the definition correctly, but you need to use the units at every stage of the calculation. 10 / 5 = 2, not 2 seconds. And 2 seconds is not the correct answer to this question.
The correct calculation, with units, is
(20 cm/s - 10 cm/s) / (9 s - 4 s).
The number 2 in your final result is, of course, correct. Including the units that result from this calculation, what is your result?
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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):
#$&* Rate of Change: 40-10/3= 30/3=10
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You need to use correct units throughout this calculation.
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• If the average rate at which position changes with respect to clock time is 5 cm / second, and if the clock time changes by 10 seconds, by how much does the position change?
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
#$&* The position changed by 5 seconds. 10-5
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This isn't correct. Try to apply the definition step by step, starting with the statement of the definition. Clearly identify the A and B quantities in the definition of the average rate of change of position with respect to clock time, and go from there.
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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):
#$&* I need to look over it as many times as possible. I can write the definition word for word and keep writing it until I do not have to look.
• You are asked in this exercise to apply the definition, and given a general procedure for doing so. Briefly outline the procedure for applying this definition, and briefly explain how you will remember to apply this procedure.
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
#$&* Using the definition, 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), I simply plugged in the corresponding numbers.
*#&!*#&!
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While you have the correct numbers in the right places on two out of the three questions, you haven't expressed any of your answers with correct units.
You need to include units throughout each calculation.
It shouldn't take you long to make the necessary corrections.
&#Please see my notes and, unless my notes indicate that revision is optional, submit a copy of this document with revisions 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.
If my notes indicate that revision is optional, use your own judgement as to whether a revision will benefit you. &#
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