Phy 121
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.
** **
The problem:
A ball starts with velocity 0 and accelerates uniformly down a ramp of length 30 cm, covering the distance in 5 seconds.
What is its average velocity?
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
Average velocity is change in distance/change in time so this is 30 cm/5 sec = 6 cm/sec
#$&*
If the acceleration of the ball is uniform then its average velocity is equal to the average of its initial and final velocities.
You know its average velocity, and you know the initial velocity is zero.
What therefore must be the final velocity?
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
Its final velocity must be 12 cm/sec because 0+12/2=6
#$&*
By how much did its velocity therefore change?
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
Its velocity changed by 12 cm/sec
#$&*
At what average rate did its velocity change with respect to clock time?
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
If it took 5 sec for the velocity to achieve 12 cm/sec then it is changing at a rate of 2.4 cm/sec.
Good, except that the units you give for your answer do not follow from the units for these quantities; see the link at the end, which I believe you will understand
#$&*
What would a graph of its velocity vs. clock time look like? Give the best description you can.
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
I think the graph would begin at 0,0 and make a gradual incline up to 12 cm/sec at 5 sec which would be 5,12. This is assuming that its velocity
increases at the steady rate above 2.4 cm/sec.
2.4 cm/sec is not a rate of change of velocity, it's a rate of change of position.
2.4 cm/sec per second would be a rate of change of velocity; 2.4 cm/s per second is also expressible as 2.4 cm/s^2.
#$&*
** **
20 min.
** **
2-3-10 at 7:35 p.m.
Any errors you have made on this assignment appear to be easily corrected. See the link indicated below. See the link listed below. You may do so if you wish, but you don't need to submit a revision unless you're unsure if you understand.
&#Please compare your solutions with the expanded discussion at the link
Solution
Self-critique your solutions, if this is necessary, according to the usual criteria. Insert any revisions, questions, etc. into a copy of this posted document. Mark any insertions with &&&& so they can be easily identified. &#