course PHY231
9/15 9pm
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?The total change in velocity is 16cm/s – 4cm/s = 12cm/s over a period of 8 seconds.
12cm/s / 8 seconds = 1.5cm/s per second increase in velocity
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?
97cm / 8.2s = the balls average velocity is 11.83cm/s
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? vF = 2 * vAve or 23.7cm/s
• What average rate is the velocity of the ball therefore changing? Over the total distance of 97cm the balls velocity increases 23.8cm/s. The average change in velocity can be found as
23.7cm/s / 8.2s = 2.89cm/s/s or an increase in velocity of 2.89cm/s every second
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?
The average velocity of the automobile is 132m/10s =13.2m/s
The final velocity is vF = 2*vAve = 26.4m/s
The average change in velocity is 26.4m/s / 10s = 2.64m/s/s
You could say that 'the average rate pf change of velocity with respect to clock time is 26.4m/s / 10s = 2.64m/s/s'
Or you could simply say that 'the requested rate is 26.4m/s / 10s = 2.64m/s/s'.
However your statement should in some appropriate way identify the result as a rate.
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