Your 'cq_1_03.1' 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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The problem:
A ball starts with velocity 0 and accelerates down a ramp of length 30 cm, covering the distance in 5 seconds.
What is its average velocity?
answer/question/discussion:
The average velocity can be determined by dividing the distance travelled by the time interval, so 30cm/5s= 6cm/s, which is velocity
If the acceleration of the ball is uniform then its average velocity is equal to the average of its initial and final velocities.
answer/question/discussion:
vAve= 6cm/s = (0+final velocity)/2= 6cm/s*2 = [(0+final velocity)/2]*2= (12cm/s)-0= (0+final velocity)-0= Final Velocity=12cm/s
You know its average velocity, and you know the initial velocity is zero. What therefore must be the final velocity?
answer/question/discussion: As shown above, 12cm/s
By how much did its velocity therefore change?
answer/question/discussion: The velocity changed 6cm/s
The velocity at the beginning of the interval was 0, and the velocity at the end was 12 cm/s. By how much did the velocity change?
At what average rate did its velocity change with respect to clock time?
answer/question/discussion: The average rate of change was 6cm/s/s
The average rate of change of velocity with respect to clock time is
ave rate = change in velocity / change in clock time.
What is the change in velocity, what is the change in clock time, and what therefore is the average rate of change of velocity with respect to clock time?
Note that you did give the right units; good work on the units.
What would a graph of its velocity vs. clock time look like? Give the best description you can.
answer/question/discussion: It would be a linear graph that starts low on the x & y axis and then increasing in a linear fashion as x and y increase.
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20min
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Almost completely correct; hopefully you'll see your one error from my notes. Try before you look at the following:
The average velocity is 6 cm/s, initial velocity is 0, and average of initial and final velocities is the average velocity, i.e. 6 cm/s.
What number would you average with 0 to get 6? The answer is 12.
So the final velocity is 12 cm/s.
The velocity changes from 0 to 12 cm/s, averaging 6 cm/s.
The change in velocity from 0 to 12 cm/s is 12 cm/s. This occurs in 5 sec so the average rate of change of velocity with respect to clock time is
ave rate = change in velocity / change in clock time = 12 cm/s / (5 s) = 2.4 cm/s/2 or 2.4 cm/s^2.