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course Phy 121
7:15 pm June 5
Seed 1 questions assignment 0#$&*
course Phy 121
9:10 pm June 3
Seed 1 questionHere 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):
quantity A= 10 cm
quantity B= 4 sec
Quantity A= 20 cm
Quantity B-=9 seconds
10 cm/4 sec= 2.5 cm a sec
20 cm/9 sec= 2.2 cm a sec
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Good listing of information.
However the average rate is not the A quantity divided by the B quantity, but the change in the A quantity divided by the change in the B quantity.
I expect you will find it easy to modify this result.
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&&&& Change in quantity A/ change in quanity B: Would subtract (20 cm -10 cm= 10 cm= change in quantity A)/ (9 sec - 4 sec= 5 sec, change in quantity b= 10/5= 2 cm per sec &&&&
• 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
30/3= 10 cm a second
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Good, but you need to use units.
40 cm/s - 10 cm/s = 30 cm/s.
Then you divide 30 cm/s by 3 s.
The number you get is 10, but since you are dividing cm/s by s the units of the quotient are not cm/s.
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&&&& 40 cm/s- 10 cm/s= 30 cm/s
30 cm/ 3 sec= 10 cm per sec &&&&
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The numerator is not 30 cm, it's 30 cm/sec.
So the calculation is
(30 cm/s) / 3 sec.
What are the correct units of the result?
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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 seconds * 5 cm would change= 50 cm a second
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There is no quantity equal to 5 cm in thie question.
There is the quantity 5 cm / sec.
So what do you get if you multiply 5 cm/s by 10 s?
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&&&& 5 cm/s * 10 s= 50 cm &&&&
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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 have memorized the new definition of a rate of change. It is important to know it word for word to ensure that you are setting up the problem the right way. You put the change of A/change of B and divide to find the answer.
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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):
I will first find what Quantity A and Quantity B are in the problem. According to rate of change, quantity A always is over quantity B and divided to find the answer. You find the change of A and the change of B and divide the two. I have memorized this definition and have looked at problem examples
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Remember, is the change in quantity A that is divided by the change in quantity B.
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You're doing well here, systematically applying the definitions.
You have missed a few details, so I'm going to ask you to revise your work. I don't think this will be difficult or time-consuming for you, since you're off to a good start.
&#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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Very good, but there is still one small part of one question (the units) that still needs to be corrected. If you understand that correction now, it won't continue to trip you up.
&#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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