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 70 mph can stop in 220 ft, how many feet will it take

Question 1113938: 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 70 mph can stop in 220 ft, how many feet will it take the same car to stop when it's traveling 140 mph?
Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
The stopping distance d of a car after the brakes are applied varies directly as the square of the speed r.
kr^2 = d
If a car traveling 70 mph can stop in 220 ft,
find k
k*70^2 = 220
4900k = 220
k = 220/4900
k = .049
how many feet will it take the same car to stop when it's traveling 140 mph?
d = .049*140^2
d = 880 ft
or a simpler way
=
= 4
d = 220 * 4
d = 880 ft
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