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course PHY 201
5/29/2012 5:25
Samantha RogersPHY 201
Random Problem 1 Version 1
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?
ANSWER:
change in velocity = 12 cm / sec
12 cm/sec / 8 sec =
average rate velocity is changing or acceleration = 1.5 cm / sec^2
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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?
ANSWER:
vAve=`ds/`dt
vAve=97cm/8.2sec = 11.829cm/sec = average velocity
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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?
ANSWER:
Final velocity is 2(vAve) = 2(11.829cm/sec) = 23.658 cm / sec
The average rate the velocity is changing, or the acceleration = 23.658cm/sec / 8.2sec = 2.885cm/sec^2
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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?
ANSWER:
First, find average velocity: vAve = 132meters/10sec = 13.2meters/sec
Final velocity is double the average = 13.2 meters/sec * 2 = 26.4meters/sec
Average rate = `dv/`dt = 26.4meters/sec / 10sec = 2.64meters/sec^2
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&#This looks very good. Let me know if you have any questions. &#