Assignment 1

course Mth 271

1/28 2

¿ÆÚõš¹’ñØü¶ß—å„Ùdw–“¬¶¼assignment #001

001. Depth vs. Clock Time and Rate of Depth Change

01-28-2010

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13:50:32

`qNote that there are four questions in this assignment.

`q001. If your stocks are worth $5000 in mid-March, $5300 in mid-July and $5500 in mid-December, during which period, March-July or July-December was your money growing faster?

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RESPONSE -->

March-july

confidence rating #$&*: 3

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13:51:10

`q002. What were the precise average rates of change during these two periods?

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Enter, as appropriate, an answer to the question, a critique of your answer in response to a given answer, your insights regarding the situation at this point, notes to yourself, or just an OK. OKIE DOKIE!

Always critique your solutions by describing any insights you had or errors you makde, and by explaining how you can make use of the insight or how you now know how to avoid certain errors. Also pose for the instructor any question or questions that you have related to the problem or series of problems.

confidence rating #$&*: 3

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13:51:39

From mid-March thru mid-July is 4 months. A change of $300 in four months gives an average rate of change of $300 / (4 months) = $75/month.

From mid-July through mid-December is 5 months, during which the value changes by $200, giving an average rate of $200 / (5 months) = $40 / month.

Thus the rate was greater during the first period than during the second.

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awesome

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Self-critique rating #$&*:ent: 3

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13:58:25

`q003. If the water in a uniform cylinder is leaking from a hole in the bottom, and if the water depths at clock times t = 10, 40 and 90 seconds are respectively 80 cm, 40 cm and 20 cm, is the depth of the water changing more quickly or less quickly, on the average, between t = 10 sec and t = 40 sec, or between t = 40 sec and t = 90 sec?

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RESPONSE -->

The water changed more quickly between T=ten seconds than any of the others.

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13:58:50

Between clock times t = 10 sec and t = 40 sec the depth changes by -40 cm, from 80 cm to 40 cm, in 30 seconds. The average rate is therefore -40 cm / (30 sec) = -1.33 cm/s.

Between t = 40 sec and t = 90 sec the change is -20 cm and the time interval is 50 sec so the average rate of change is -20 cm/ 50 sec = -.4 cm/s, approx.

The depth is changing more quickly during the first time interval.

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ok

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Self-critique rating #$&*:ent: 3

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14:01:55

`q004. How are the two preceding questions actually different versions of the same question? How it is the mathematical reasoning the same in both cases?

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Both questions were asking about the change in events and in which case did it change the greatest. in both cases i had to break down how much change occured in the same amout of time, the first question i had to break it down to per month and the second i had to break it down per second.

confidence rating #$&*: 3

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14:03:11

In each case we were given a quantity that changed with time. We were given the quantities at three different clock times and we were asked to compare the rates of change over the corresponding intervals. We did this by determining the changes in the quantities and the changes in the clock times, and for each interval dividing change in quantity by change in clock time. We could symbolize this process by representing the change in clock time by `dt and the change in the quantity by `dQ. The rate is thus rate = `dQ /`dt.

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ok

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Self-critique rating #$&*:ent: 3

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&#This looks good. Let me know if you have any questions. &#