#$&*
Phys201
Your 'cq_1_02.1' report has been received. Scroll down through the document to see any comments I might have inserted, and my final comment at the end.
** CQ_1_02.1_labelMessages.txt **
ball starts with velocity 4 cm/sec and ends with a velocity of 10 cm/sec.
• What is your best guess about the ball's average velocity?
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
ave vel=`ds/`dt
ave vel=(10-4)/1sec
ave vel= 6 cm/sec
@&
(10 - 4) / (1 s) = 6 / s, not 6 cm/s.
(10 cm/s - 4 cm/s) / (1 s) = 6 cm/s^2, which is not a velocity. This calculation would correspond to the average rate of change of the velocity, were the velocity to have changed during a 1-second time interval.
It's good that you are trying to apply the rate definition, but it is unnecessary for the current question.
What was the velocity at the beginning of the interval, what was the velocity at the end, and how much did the velocity therefore change.
*@
I am assuming here that the time change would be 1 sec. This information is not directly given. I think this is why the question is asking for your best guess.
#$&*
• Without further information, why is this just a guess?
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
It is just a guess because we have no information that states if it was traveling at a constant velocity or not. We are also assuming its 1 sec because those values are not given.
#$&*
• If it takes 3 seconds to get from the first velocity to the second, then what is your best guess about how far it traveled during that time?
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
vAve=(10-4)/3sec
@&
You haven't used units for all quantities in this calculation.
*@
vAve=2 cm/sec
I used the equation vAve=`ds/`dt. Am I using the correct equation?
@&
You should think more basically, in terms of the definition of velocity as an average rate of change.
That definition does, however, lead directly to the equation you quote.
*@
#$&*
• At what average rate did its velocity change with respect to clock time during this interval?
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
vAve=`ds/`dt
vAve/`ds=`dt
2/6=3 cm/sec
??? Not certain that I did this correctly. My thought was to manipulate the equation to find `dt.
@&
You need to analyze this question in terms of the definition of average rate of change.
The question does not involve the average velocity, but the average rate of change of the velocity.
*@
#$&*
*#&!
@&
You need to use units throughout your calculations, for a number of reasons.
You also need to think consistently in terms of the definition of average rate of change. You are on the verge of doing so.
&#Please see my notes and submit a copy of this document with revisions, comments and/or questions, and mark your insertions with &&&& (please mark each insertion at the beginning and at the end).
Be sure to include the entire document, including my notes. &#
*@