Randomized Problems 4

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course Phy 121

9/22/10 12:13 pm

An automobile traveling a straight line is at point A at clock time t = 4 sec, where it is traveling at 10 m/s, to point B at clock time t = 11 sec, where it is traveling at 20.5 m/s. Point A is 75 meters from the starting point and point B is 115 meters from the starting point. What are the average velocity and the average

acceleration of the automobile during the specified time? What evidence is there that the acceleration is or is not uniform?

20.5 m/s - 10 m/s = 10.5 m/s

11 sec - 4 sec = 7 sec

10.5 m/s / 7 sec = 1.5 m/s

10.5 m/s / 7 sec = 1.5 m/s^2

The number is not negative so evidence there is acceleration."

see my note on units; otherwise well done

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