course Phy 201 assignment #001001.
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01:35:40 Explain in your own words how the standard deviation of a set of numbers is calculuated.
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RESPONSE --> Standard deviation is obtained by taking the deviations of numbers from their mean. Next we squared those numbers and took the average of the squared numbers. Lastly we took the square root of the average of squared deviations to obtain the standard deviation. confidence assessment: 3
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01:40:17 Explain in your own words the process of fitting a straight line to a graph of y vs. x data, and briefly discuss the nature of the uncertainties encountered in the process. For example, you might address the question of how two different people, given the same graph, might obtain different results for the slope and the vertical intercept.
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RESPONSE --> When fitting a straight line to a graph of y vs. x data you have to try to eyeball the straight line that is closest to all the data points. When doing this you have to obtain horizontal and vertical coordinates to figure out the slope and find the y-intercept. These figures are entered into the equation y=mx+b which become the equation for the line of best fit for that particular graph. Two different people may obtain different slopes and y-intercepts for the same graph because they may eyeball the data differently and they may also estimate the line of best fit steeper, lower, etc. confidence assessment: 2
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01:42:22 Briefly state what you think velocity is and how you think it is an example of a rate.
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RESPONSE --> Velocity is the rate of change of position. It is an example of rate because it can also be seen as the rate of change in an object. Rate is complementary to the word velocity because rate can refer to speed, acceleration, etc. confidence assessment: 2
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01:43:27 ** A rate is a change in something divided by a change in something else. This question concerns velocity, which is the rate of change of position: change in position divided by change in clock time. **
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RESPONSE --> ok self critique assessment:
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01:46:40 Given average speed and time interval how do you find distance moved?
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RESPONSE --> Distance moved is found by multiplying average speed by the time interval. For example, speed could be measured in m/s and time interval in s so the seconds would cancel out leaving the distance moved in meters. confidence assessment: 2
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01:47:30 ** You multiply average speed * time interval to find distance moved. For example, 50 miles / hour * 3 hours = 150 miles. **
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RESPONSE --> Sounds great! self critique assessment: 3
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01:49:18 Given average speed and distance moved how do you find the corresponding time interval?
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RESPONSE --> Distance moved divided by average speed would give the corresponding time interval. confidence assessment: 2
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01:50:55 ** time interval = distance / average speed. For example if we travel 100 miles at 50 mph it takes 2 hours--we divide the distance by the speed. In symbols, if `ds = vAve * `dt then `dt = `ds/vAve. Also note that (cm/s ) / s = cm/s^2, not sec, whereas cm / (cm/s) = cm * s / cm = s, as appropriate in a calculation of `dt. **
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RESPONSE --> self critique assessment:
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01:52:58 Given time interval and distance moved how do you get average speed?
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RESPONSE --> Time interval divided by distance results in average speed. If we have travel 100 miles in 2 hours we divide the time interval, 100 miles, by the distance, 2 hours, to see that the average speed is 50 mph. confidence assessment: 3
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01:53:05 ** Average speed = distance / change in clock time. This is the definition of average speed. For example if we travel 300 miles in 5 hours we have been traveling at an average speed of 300 miles / 5 hours = 60 miles / hour. **
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RESPONSE --> self critique assessment: 3
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[ʃSycHl assignment #003 t鈰׳þl Physics I Class Notes 06-12-2008 Ǒ裛̻ڮʅ} assignment #001 t鈰׳þl Physics I Vid Clips 06-12-2008
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23:41:43 Physics video clip 01: A ball rolls down a straight inclined ramp. It is the velocity the ball constant? Is the velocity increasing? Is the velocity decreasing?
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RESPONSE --> The velocity of the ball is constant.
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23:43:02 ** It appears obvious, from common experience and from direct observation, that the velocity of the ball increases. A graph of position vs. clock time would be increasing, indicating that the ball is moving forward. Since the velocity increases the position increases at an increasing rate, so the graph increases at an increasing rate. **
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RESPONSE -->
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23:44:11 If the ball had a speedometer we could tell. What could we measure to determine whether the velocity of the ball is increase or decreasing?
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RESPONSE --> We could measure the initial velocity and the final velocity as well as the time intervals and distance measured.
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23:46:51 A ball rolls down ramp which curves upward at the starting end and otherwise rests on a level table. What is the shape of the velocity vs. clock time graph for the motion of the ball?
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RESPONSE --> ok
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23:47:48 ** While on the curved end the ball will be speeding up, and the graph will therefore rise. By the time the ball gets to the level part the velocity will no longer be increasing and the graph will level off; because of friction the graph will actually decrease a bit, along a straight line. As long as the ball is on the ramp the graph will continue on this line until it reaches zero, indicating that the ball eventually stops. In the ideal frictionless situation on an infinite ramp the line just remains level forever. **
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RESPONSE --> ok
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