#$&*
course PHY 201
1/28 6:42PM
If the velocity of the object changes from 4 cm / sec to 16 cm / sec in 8 seconds, then at what average rate is the velocity changing?
A ball rolling from rest down a constant incline requires 8.2 seconds to roll the 97 centimeter length of the incline.
What is its average velocity?
An object which accelerates uniformly from rest will attain a final velocity which is double its average velocity.
What therefore is the final velocity of this ball?
What average rate is the velocity of the ball therefore changing?
An automobile accelerates uniformly down a constant incline, starting from rest. It requires 10 seconds to cover a distance of 132 meters. At what average rate is the velocity of the automobile therefore changing?
1. The change in velocity from 4 to 16 secs is 12 cm/sec. Divide that by the change in time, 8 seconds, yields 1.5 cm/sec as the average rate velocity is changing.
@&
If you divide 12 cm/s by 8 s you get 1.5 cm/s^2, not 1.5 cm/s.
*@
2. The average velocity is 97 cm / 8.2 secs.
3. vf = 2 vAve, then vAve = vf / 2.
@&
The question doesn't ask for vAve or vf, but for the average rate at which the velocity is changing.
You need to start with the definition of average rate of change and work this out.
*@
4. vAve = 13.2 m/ sec, ???? don't think that is right. Don't know what the final velocity would be. "
@&
The automobile starts from rest. So the reasoning of the preceding problem could be used here.
*@
@&
&#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. &#
*@