course Phy 121
Problem1If the velocity of the object changes from 5 cm / sec to 15 cm / sec in 9 seconds, then at what average rate is the velocity changing?
15 cm/sec-5 cm/sec= 10 cm/sec
10 cm/sec/ 9 sec= 1.11 cm/ sec/ sec
A ball rolling from rest down a constant incline requires 3.9 seconds to roll the 49 centimeter length of the incline.
• What is its average velocity?
49 cm/ 3.9 sec= 12.56 cm/ sec
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?
Final velocity= 2*vAVE
• What average rate is the velocity of the ball therefore changing?
vAVE= final velocity/2
this would be ave velocity, not ave rate of change of velocity
An automobile accelerates uniformly down a constant incline, starting from rest. It requires 13 seconds to cover a distance of 110 meters. At what average rate is the velocity of the automobile therefore changing?
110 meters/ 13 seconds= 8.46 meters/sec
this is ave velocity, which you can use in the process of finding ave rate of change of velocity
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