SCENARIO+1

Stop Light Violations




====It's 1am on a Tuesday morning. Harrison decides to take a drive into Center City to see the bright city lights. He gets into his car and begins to drive, from a rest position. The streets are clear, and there's hardly any traffic. The speed limit for his neighborhood street is 30. When Harry reaches the express way, he begins to speed up. The speed limit for the express way changes to 60 miles per hour. He is driving at a speed of 60 (26.28 m/s) miles per hour until he reaches the end of the express way. As he approaches the end of the road, the traffic light suddenly changes to yellow. The yellow light takes about 4 seconds before it changes to red. ====

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 From the problem, we determined that the final velocity was 26.28 m/s. By looking at an online resource about stopping distances for cars, we determined that the displacement of the stopped car (going at approximately 100 k/h) is 77.7 m. After creating a velocity v.s. time graph, we can see that a triangle has formed. By using the area of a triangle formula, we can determine what "t" or the base of the triangle is, thus allowing us to find the acceleration (a). =====

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 Then, we can use the slope formula to find a, because we now have four points on the graph. =====

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 So the breaking acceleration for a car stopping after going 26.28m/s is -4.44m/s/s. It must stop in -4.44m/s/s or less for it to not run a red light. =====

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 Using the formula for change in displacement, we can determine the acceleration for the car stopping at various distances and compare it to the actual breaking acceleration. =====

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 So, the acceleration of the breaking of the car would be -12.37m/s/s if the car stops 5 meters away from the end of the road. =====

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 So the acceleration of the car, stopping 10 meters away from the end of the road, is -11.75 m/s/s. =====

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<span style="display: block; font-family: Arial,Helvetica,sans-serif; font-size: 120%; text-align: center;"> So the acceleration of the car, stopping 25 meters away from the end of the road, is -9.87m/s/s. =====

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<span style="display: block; font-family: Arial,Helvetica,sans-serif; font-size: 120%; text-align: center;"> In our calculations, we found that the greater the displacement, the lesser the over all acceleration. We also found that the car must stop in less that -4.44 m/s/s for it not to run a red light. After analyzing this data, we have come to the conclusion that the more distance one has, the less acceleration occurs. So, when a driver is braking, it is best to have a greater distance away from the end of the road, that way the driver has a greater chance of stopping in time and not running a red light. If the driver does not allow him/herself the appropriate time to stop before the yellow light turns red, the driver risks the chance of causing a collision. This is not beneficial to maintaining safe driving regulations. =====

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<span style="display: block; font-family: Arial,Helvetica,sans-serif; font-size: 120%; text-align: center;"> (2007). //Stopping distances for cars-road safety authority of the road//. Retrieved from http://www.rulesoftheroad.ie/rules-for-driving/speed-limits/speed-limits_stopping-distances-cars.html =====

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<span style="display: block; font-family: Arial,Helvetica,sans-serif; font-size: 120%; text-align: center;"> (2009, August 7). //find reviews by make share4 the truth about cars » crime & punishment » news blog georgia: increased yellow lights saves lives, kills cameras//. Retrieved from http://www.thetruthaboutcars.com/georgia-increased-yellow-lights-saves-lives-kills-cameras/ =====