SOLUTION: The stopping distance d of a car after the brakes are applied varies directly as the square of the speed r. If a car travelling 70 mph can stop in 270 ft, how many feet will it ta

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Question 326995: The stopping distance d of a car after the brakes are applied varies directly as the square of the speed r. If a car travelling 70 mph can stop in 270 ft, how many feet will it take the same car to stop when it is travelling 20 mph.

Answer by jvan(28) About Me  (Show Source):
You can put this solution on YOUR website!
Let's write an equation for this problem, "stopping distance d of a car after the brakes are applied varies directly as the square of the speed r": d=c%2Ar%5E2. With c being the constant. Plugging in 70mph and 270feet you get: 270feet=c%2A%2870%5E2%29. Divide both sides by 70^2 to get c=0.055. Now that you have found c, let's find the stopping distance of the car if it where traveling at 20mph. The equation 270=c%2A%2870%5E2%29 becomes d=0.055%2A%2820%5E2%29 after you plug in the c and r. Then you find that d=22+feet. Hope this helps :D!!!!
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