Mth 163
Your 'cq_1_02.1' 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:
A ball starts with velocity 4 cm/sec and ends with a velocity of 10 cm/sec.
• What is your best guess about the ball's average velocity?
answer/question/discussion:
Adding the two rates and averaging I get
4cm/sec + 10cm/sec = (14cm/sec) / 2 =
vAve = 7cm/sec
• Without further information, why is this just a guess?
answer/question/discussion:
Because without having several instances of time intervals to compare rate increase, and acceleration we cannot determine the exact rate of increase.
• If it takes 3 seconds to get from the first velocity to the second, then what is your best guess about how far it traveled during that time?
answer/question/discussion:
If we are using the velocity increases from the first question then we would have an average rate of (7cm/sec) * ( 3sec) =
vAve = 21cm
• At what average rate did its velocity change with respect to clock time during this interval?
answer/question/discussion:
If the velocity at the first interval was 4cm/sec and 10cm/sec at bthe second interval and total time of 3sec, then we have final velocity – initial velocity / total time =
(10cm/sec – 4 cm/sec) / 3sec = 2cm/sec
The units of this calculation are not correct. The numerator comes out 6 cm/s, your denominator has units of seconds. What therefore are the units of the numerator divided by the units of the denominator?
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45 min
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Very good work, except for the error on the units.
The units of that last calculation should have been cm/s^2. If you aren't sure how this is work out, let me know.