course Phy 121
I have reviewed and corrected this assignment.
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Multiplying time interval by change in velocity does not give a meaningful quantity.
Since vAve = `ds / `dt, the we see that `ds = vAve * `dt: displacement = average velocity * time interval.
Please submit a revised solution to the last part of this problem, and be sure to include my notes.
WEEK 2, QUIZ 1:
If an object increases velocity at a uniform rate from 7 m/s to 21 m/s in 11 seconds, what is its acceleration and how far does it travel?
Acceleration is the average rate of change in velocity. It is expressed by the formula: `dv/`dt. The change in velocity is: 21m/s - 7m/s = 14m/s. The change in time is 11 seconds.
Acceleration = (14m/s)/11s = 1.27m/s^2.
Distance traveled can by found by multiplying time interval, 11 seconds, by the change in velocity: (11s)(14m/s) = 154 cm
Sketch a velocity vs. clock time graph for an object whose initial velocity is 7 m/s and whose velocity 11 seconds later is 21 m/s. Explain what the slope of the graph means and why, and also what the area means and why.
**I have emailed my graph.
The slope of the velocity vs. clock time represents the rate of change in velocity or acceleration. The slope of this graph is linear which implies that acceleration is constant.
Rise = Change in velocity = 21m/s - 7m/s = 14m/s
Run = Change in time = 11s - 0s = 11s
Slope = rise/run = (14m/s)/(11s) = 1.27 m/s^2
The area under the graph represents average velocity multiplied by the time interval, which is the displacement. The average altitude of the interval under the graph represents average velocity and the width represent the time interval.
Area = `ds = (vAve)(`dt) = (altitude)(width)
Altitude = height at midpoint = (21m/s - 7m/s)/2 = (14m/s)/2 = 7m/s
Width = time interval = 11s
`ds = (vAve)(`dt) = (7m/s)(11s) = 77m
You need to be very specific in your description of the meaning of your graph. Everything you say here is correct, but you should specify the exact rise and run of your graph, describe exactly how they give you the slope and what the result is, etc.. Similar detail should be included in your interpretation of the area.
Please submit that information along with the other details of this problem, including my notes.
Most of your answers are good, and you are very close to putting all this together very nicely. Please resubmit the requested work and let me know if you have questions."
Good revision. Let me know if you have questions.