Problema 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 traveling 30mph can stop in 50ft, how many feet will it take the same car to stop when it is traveling 80 mph?

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solution

d = k*r^2

So when r = 30 mph, d = 50 ft

so k = 50/30^2 = 1/18

So d = 1/18 * 80^2 = 355.56 ft

it takes 355.56 ftwhen it is traveling 80 mph