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 40mph can stop in 90ft, how many feet will it take fo

Question 555141: 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 40mph can stop in 90ft, how many feet will it take for the same car to stop traveling 90 mph?
It will take ______ft.
Please help with this word problem. Thank you.

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.
If a car traveling 40mph can stop in 90ft, how many feet will it take for the same car to stop traveling 90 mph?
:
Find the constant of variation, k:
k*R^2 = D
R = 40, D = 90
k*40^2 = 90
1600k = 90
k =
k = .05625
:
D = .05625R^2; the equation
At 90 mph
D = .05625*90^2
D = 455.625 ft at 90 mph
:

RELATED QUESTIONS
The stopping distance d of a car after the brakes are applied varies directly as the... (answered by ccs2011)

inverse variation, direct variation, joint and combined the stopping distance d of a... (answered by Nate)

I have tried this one several times and can not get the answer. The stopping distance d... (answered by ankor@dixie-net.com)

The stopping distance d of a car after the brakes are applied varies directly as the... (answered by Mathtut)

The stopping distance D of a car after the brakes are applied varies directly as the... (answered by checkley77)

The stopping distance d of a car after the brakes are applied varies directly as the... (answered by josmiceli)

The stopping distance d of a car after the brakes are applied varies directly as the... (answered by jvan)

Please help! The stopping distance d of a car after the brakes are applied varies... (answered by stanbon)

the stopping distance d of a car after the brakes are applied varies directly as the... (answered by TeishaRenee)

Please help! The stopping distance d of a car after the brakes are applied varies... (answered by stanbon,josmiceli,Alan3354)