video clips 7

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09:16:16 Video Clip 7: Slope triangle, instantaneous acceleration, tangent line How do we represent the calculation of the rate which velocity changes on graph of velocity vs. time?

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RESPONSE --> You could calculate the slope to represent the rate which velocity changes. (Change in velocity over change in time)

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09:16:21 ** Correct response from student: We can represent the rate of velocity change by calculating the slope. Slope is rise/run which is change in velocity/change in time **

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RESPONSE --> ok

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09:21:50 If we know the velocity at every clock time, that how we find the precise rate at which velocity changes adding given clock time?

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RESPONSE --> You would calculate the slope over the different clock times at smaller points or intervals at certain periods.

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09:21:55 ** STUDENT RESPONSE: I am not sure I understand, however I think you would make a triangle between the two times and velocities--i.e., between the two points on the v vs. t graph. Then find slope. INSTRUCTOR CRIQITUE: You would do this, but you would calculate the rate or slope over smaller and smaller intervals containing the clock time at the specified instant. You would try to determine the limiting value as the interval approaches 0. This limiting value is the instantaneous rate as well as the slope of the tangent line. **

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RESPONSE --> ok

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09:25:45 How do we depict the instantaneous rate of velocity change on a graph of velocity vs. time?

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RESPONSE --> You would try to determine the limiting value as the interval approaches 0. This is how you depict the instantaneous rate of velocity change on a graph of velocity vs. time

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09:26:02 ** See the preceding answer. **

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RESPONSE --> That is where I found the answer.

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09:32:32 Physics video clips 08: Finding displacement: define displacement, then calculate by common sense, by formula, by area What is the difference between displacement and distance?

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RESPONSE --> Displacement is the change in position, or how far an object moved. The difference between displacement and distance is that displacement can be positive or negative (forward/backward) and distance is always positive.

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09:32:38 ** Displacement tells the change in position, which is the same as distance but displacement can have a negative or positive value whereas distance is always positive. **

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RESPONSE --> ok

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09:36:52 How do we calculate displacement from velocity and time interval?ÿ What is the common sense of this calculation?

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RESPONSE --> If the average velocity tells us how far an object travels in one second, then we multiply it by the time interval, it will tell us how far the object travels in that amount of time.

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09:36:59 ** Correct response from student: The vAve multiplied by the time interval. If the vAve tells us how far it travels one second, then if we multiply it by the time interval it will tell us how far it will travel in that amt. of time. **

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RESPONSE --> ok

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09:45:14 How do we use a graph to help visualize the calculation of displacement when velocity is constant?

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RESPONSE --> The graph will be a straight line, with the displacement corresponding to the clock times.

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09:45:31 02-05-2006 09:45:31 ** Since the vel. is constant, a graph of velocity vs. clock time over a given time interval will form a rectangle whose 'height' represents the velocity and whose width represents the time interval. Multiplying velocity * time interval gives displacement. A graph of position vs. clock time will be a straight-line graph, and the displacement corresponding to two clock times will be the change in the y coordinate between those clock times. **

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NOTES -------> Since the vel. is constant, a graph of velocity vs. clock time over a given time interval will form a rectangle whose 'height' represents the velocity and whose width represents the time interval. Multiplying velocity * time interval gives displacement.

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09:50:25 What aspect of a v vs. t graph tells us the displacement?

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RESPONSE --> Displcaement corresponds with the two clock times on the graph, and the area of the rectangle formed between the two given clock times will indicate the displacement, as stated in the previous answer to the last question.

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09:50:29 ** The area of the rectangle formed between the two given clock times will indicate the displacement (see preceding comment). **

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RESPONSE --> ok

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