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# Speed and Velocity

1) Jack travels from A to B at 30mph and returns at 10mph. Jill leaves at the same time as Jack, and travels from A to B and back at a constant speed of 20mph. Who gets back first?

2) Assume that East Lak Road runs due east from the Walmart and there are markers along it, ten miles from walmart, etc. a car starts at the 12 mile marker at 3pm, and stops at the 8 mile marker at 4pm. What is the total displacement of the car from 2pm to 4pm, in miles?

3) In the previous question what is the average velocity of the car during the trip from 2pm till 4pm, in miles/hour?

4) In question 2, what was the average speed of the car between 2 pm and 4pm? That is, what was the average speedometer reading in miles/hour?

#### Solution Preview

1. Time = distance / speed. Or t = d/s.
Jack t = d/30 + d/10 = 4d/30
Jill t = d/20 + d/20 = d/10
Regardless of the distance, it takes Jack longer than Jill. 40/30 > 1/10

2. Displacement = (final ...

#### Solution Summary

This solution includes calculations and answers for (1) through (4).

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