course phy 201
Good job, but you have one error on the last problem. See my note and please do as it says.
If anything is not clear let me know, and include as many specifics as possible.
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 average rate is the velocity changing is actually the average acceler
To find the average acceleration you (final velocity – initial velocity) / time interval.
(16 cm/s – 4cm/s) / 8s = 1.5cm/s^2
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?
The average velocity is the same thing as the average rate at which its position changes and the average rate. This is the change in position divided by the change in clock time
Vave – (final position – initial position)/ time elapsed
(97cm – 0)/ 8.2s = 11.8cm/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?
Then the final velocity of the ball would be the average velocity multiplied by 2.
11.8cm/s * 2 = 23.6cm/s is the final velocity.
• What average rate is the velocity of the ball therefore changing?
Acceleration = (final velocity – initial velocity) / time interval
Final velocity was 23.6cm/s
Initial velocity is 0cm/0s
Time interval was 8.2s
(23.6cm/s – 0cm/0s) / 8.2s = 2.9cm/s^2
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?
First you find the final velocity which is 132m / 10s = 13.2m/s
This is the average velocity, not the final velocity. It's important to distinguish the two. Send me a correction on this problem. See the process used in the preceding series of problems, which you followed correctly here except for one step.
I think you'll understand but if not questions are also welcome.
The initial velocity is 0m/s because it starts from rest.
So the average rate the velocity is change = acceleration = (final velocity – initial velocity) / time interval
Acceleration = (13.2m/s – 0m/s) / 10s = 1.32m/s^2
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