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course phy 201
9/5 1 am
Questions `q001 - `q004 are for everybody.Questions `q005 - `q007 require the use of calculus and are for University Physics students only.
`q001. This series of questions uses the basic analysis of a straight-line v vs. t graph for an object which starts from rest:
Sketch a v vs. t graph representing the motion of a ball that starts from rest and moves for 6 seconds, averaging a velocity of 15 cm / sec.
Describe your graph.
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The graph has velocity on the y axis and time on the x axis. The graph is rising to the right at a constant rate. The average velocity is at 15cm/sec and the final is at 30 cm/sec.
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What are the initial and final velocities of the ball?
**** Initial = 0 Final = 30 cm/sec
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What is its velocity at the 3-second mark?
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15 cm/sec
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By how much does its velocity change during the 6-second time interval?
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Changes from 0 to 30 cm/sec
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How quickly is its velocity changing during the 6-second interval? Note that the answer to this question is also the slope of your v vs. t graph.
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5 cm/sec^2
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`q002. This question asks you to do something closely related to today's class, but somewhat different from anything we actually did.
How far does the ball in the preceding question travel during the 6 second interval?
**** 90 cm
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How far does it travel during the first 3 seconds?
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3*15 =45 45/2 = 22.5 cm.....I don't really understand how to do this question..
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Will its average velocity during the first 3 seconds be as high as the average velocity for the 6-second interval?
If not, what do you think the average velocity would be for the first 3 seconds?
With that average velocity, how far would the object travel?
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Would a sketch of its position vs. clock time be a straight line, a rising curve with an increasing slope, a rising curve with a decreasing slope, or some other type of curve?
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The sketch would be a rising curve with an increasing slope because of the ball picking up speed and momentum.
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`q003. Report your data from today's experiment. Your report should be clear and concise, telling the reader what was measured and how, and specifically what the results were.
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In todays experiment, a marble was rolled 30 cm. It toke 2 1/2 pendulum oscillations to complete the 30 cm. The pendulum was 20 cm long. The marble traveling at an avg of 12cm/sec and a final velocity of 24 cm/sec.
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Velocities would more likely be 12 cm/cycle and 24 cm/cycle, but a cycle of that pendulum would be fairly close to 1 second.
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`q004. For one of your ramps, indicate the displacement of the ball and the number of cycles of your pendulum corresponding to motion to or from rest in one direction, and the displacement of the ball and the number of cycles to or from rest in the other direction.
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With the ball rolling from the front of the class toward the back of class. The ball rolled 30cm in 2.5 oscillations. That means that the avg velocity was 12 cm/sec with a final velocity of 24 cm/sec, slope is 9.6 cm/sec^2....When the ball rolled from the back of class toward the front, the ball rolled on 17 cm in 4 oscillations..Avg velocity was 4.25 cm/sec, final velocity was 8.5 cm/sec, slope is (4.25/2) cm/sec^2
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What is the average velocity of the ball as it travels in each direction, according to your data? Your time will be measured in cycles of the pendulum, rather than in seconds. A cycle is a perfectly valid unit of time, as long as you know the length of the pendulum. So for example the average velocity of the ball will be in centimeters / cycle. We can later convert the result to units involving seconds.
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Front to back of room is 12cm/cycle......Back of room to front is 4.25cm/cycle
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What are the initial and final velocity of the ball in each direction?
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Front to back of room was 0 to 24cm/Cycle.....Back of room to front was 0 to 8.5cm/Cycle
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What is the change in velocity in each direction?
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Front to back of room was 24cm/cycle....back of room to front was 8.5cm/cycle
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How quickly did velocity change in each direction? Note that an answer to this question is also the slope of an appropriate v vs. t graph.
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Front to back of room was 9.6cm/cycle^2....back of room to front was 2.125cm/cycle^2
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&#Your work looks good. See my notes. Let me know if you have any questions. &#