PHY 201
Your 'cq_1_04.1' 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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Seed question 4.1
The problem:
A ball is moving at 10 cm/s when clock time is 4
seconds, and at 40 cm/s when clock time is 9 seconds.
Sketch a v vs. t graph and represent these two events
by the points (4 sec, 10 cm/s) and (9 s, 40 cm/s).
answer/question/discussion: I sketched this
Sketch a straight line segment between these points.
answer/question/discussion: It is increasing at a
constant rate
What are the rise, run and slope of this segment?
answer/question/discussion:
Rise or 'dy = 30 m/s
Run or 'dx = 5 seconds
The slope therefore is 6 m/s/s and this is the average
acceleration of the object also.
What is the area of the graph beneath this segment?
answer/question/discussion:
I think of it as a right triangle setting on top of a
rectangle. Measurements are:
Base of traingle: 5
Heighth of tri: 30
Length of rectangle: 5
Width of rectangle: 10
So the area of the triangle would be 75
Area of rectangle would be 50
The total area under the segment to the x axis is 125.
If you added the velocity of the ball at each second
then you would get A different answer though.
At 4 seconds it was 10 m/s
At 5: 16
At 6: 22
At 7: 28
At 8: 34
At 9: 40
Add them up and you get 150. It's off by the average
This is an easy error to make. The following should clarify it:
You've added six velocities to get the distance moved in 5 seconds.
If you add the average velocities for each of the five 1-second intervals your answer will agree with your previous answer.
velocity of 25 m/s. I guess this could be because we
added 6 velocities but only had a change in time of 5
seconds. I can't say I quite understand the importance
of the total area beneath the line segment.
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30 minutes
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For the purposes of interpretation, you want to look at the trapezoid as a single object, not a triangle on top of a rectangle.
&#At least part of your solution does not agree with the solution and comments given at the link below. You should view the solution at that link and self-critique as indicated there.
Solution
This link also expands on these topics and alerts you to many of the common errors made by students in the first part of this course. &#