Your 'cq_1_02.2' report has been received. Scroll down through the document to see any comments I might have inserted, and my final comment at the end.
** **
The problem:
A graph is constructed representing velocity vs. clock time for the interval between clock times t = 5 seconds and t = 13 seconds. The graph consists of a straight line from the point (5 sec, 16 cm/s) to the point (13 sec, 40 cm/s).
1. What is the clock time at the midpoint of this interval?
9s
I subtracted 5s from 13s to get 8s which I then divided by 2 to get 4s. I added 4s to 5s to get the clock time at the midpt. which would be 9s.
2. What is the velocity at the midpoint of this interval?
28cm/s
I subtracted 16cm/s from 40cm/s to get 24 which I then divided by 2 to get 12. I added 12 to 16 to get the velocity at the midpt. which would be 28cm/s.
3. How far do you think the object travels during this interval?
224cm
I multiplied the rate of 28cm/s and the time of 8s to get the distance traveled of 224cm.
4. By how much does the clock time change during this interval?
8s
I subtracted 5s from 13s.
5. By how much does velocity change during this interval?
24cm/s
I subtracted 16cm/s from 40cm/s to get 24cm/s.
6. What is the rise of the graph between these points?
24cm/s
y2 - y1 = 40 - 16 = 24cm/s
7. What is the run of the graph between these points?
8s
x2 - x1 = 13 - 5 = 8s
8. What is the slope of the graph between these points?
3cm/s^2
y = mx+b, m = (y2 - y1)/(x2 - x1) = 24/8 = 3cm/s^2
9. What does the slope of the graph tell you about the motion of the object during this interval?
The velocity of the object is increasing, that is, it is accelerating.
10. What is the average rate of change of the object's velocity with respect to clock time during this interval?
3cm/s^2
a = `dv/`dt = (40 - 16)/8 = 3cm/s^2
** **
20 min.
** **
Please respond relative to goal of C.
Good. I believe before you had 3.125 cm/s^2 for the acceleration, or something of that nature, and while I could easily guess at the nature of the error it wasn't clear what you had to get the result.
I ask for documentation for a lot of reasons. One important reason is that I can't grade you on what I think your answer might mean; this is an important issue on tests.