Question 415241
The stopping distance d of a car after the brakes are applied varies directly as the square speed r?
if a car traveling 30 mph can stop in 50 feet, how many feet will it take the same car to stop when it is traveling 90 mph?
:
Let k = constant of variation
:
d = k*r^2
When d = 50 and r = 30
k *30^2 = 50
900k = 50
k = 50/900
k = .0556
:
"how many feet will it take the same car to stop when it is traveling 90 mph?"
d = .0556 * 90^2
d = .0556 * 8100
d ~ 450 ft for a car going 90 mph to stop