A hare and a tortoise compete in a race over a straight course 1.45 km long. The

Question

A hare and a tortoise compete in a race over a straight course 1.45 km long. The tortoise crawls at a speed of 0.100 m/s toward the finish line. The hare runs at a speed of 7.05 m/s toward the finish line for 1.160 km and then stops to tease the slow-moving tortoise as the tortoise eventually passes by. The hare waits for a while after the tortoise passes and then runs toward the finish line again at 7.05 m/s. Both the hare and the tortoise cross the finish line at the exact same instant. Assume both animals, when moving, move steadily at their respective speeds.
(a) How far is the tortoise from the finish line when the hare resumes the race?
1 m

(b) For how long in time was the hare stationary?

Explanation / Answer

I like askers that don't just want the answer but want to learn something! First use d=vt to find out how long it is going to take the tortoise complete the race. Then use d=vt to find the time it took the hare to get to his stopping point.(Note you have to convert km to meters.) Find the difference to see how much time the hare has left. Then use that time and the tortoise's speed in the equation v=dt to find the distance the tortoise will be away from the finish line before the hare has to get going. This is a really good question to exercise one's use of the v=dt equation. And it also really works one's problem solving skills. Work to understand it fully. Just in case you don't know something very important the physics teachers don't seem to be teaching, I've also copied and pasted the below. It not relevent to you question however. ========== How to convert units is a very common question in Yahoo Answers. The below is a very powerful and easy method to convert numbers from one unit to another. While this has been "Copied and Pasted" it has been written by me. Let us take an easy example. Say you have 2.7 meters and you want to convert it to centimeters. You know that 1m = 100 cm Think about how the equation 1m = 100 cm can be rearrange to 1= 100 cm/m. Now think about how it is that if you multiply 2.7m by the number 1 you simply get 2.7m again. Now think about how since "100 cm/m" equals 1 you can multiply 2.7 m by "100 cm/m" and you will have the same distance. The only difference is that after you cancel out the meters the distance will be expressed in different units. Here it is expresses mathematically... 2.7m = 2.7m X 1 = 2.7m X 100 cm/m = 270 cm. Notice how the meters cancel each other out and you are left with centimeters. This always works Here is a harder example. Convert 8,730 seconds to minutes. Since 1 minute equals 60 seconds, 1min = 60 sec or rearranged 1 = 60 sec/min In this case you have to divide by 1 or divide by 60 sec/min to cancel out the seconds. Here is the math. 8,730 sec = 8,730 sec / 1 = 8,730 sec / (60 sec/min) = 145.5 min. Notice again how the seconds cancel out and you are left with minutes. You could have instead converted the equation 1min = 60 sec to (1/60)min/sec = 1 and then multiplied by it like below. 8,730 sec = 8,730 sec X 1 = 8,730 sec X (1/60)min/sec = 145.5 min. Again the seconds cancel out. For some reason it is not the law for physic teachers to tell their students about it. Here is website that goes into it in more detail. http://oakroadsystems.com/math/convert.h…

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