<PRE><B>Question 439458</B>
The braking distance D in feet required to stop a car traveling x mph on dry, level pavement can be approximated by D= (1/9)x^2
(a.) Calculate the braking distance for 30 mph and 60 mph. how do your answers compare?
D(30) = (1/9)*30^2 = 100 ft.
D(60) = (1/9)*60^2 = 400 ft.
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(b.) If the braking distance is 16 feet, estimate the speed of the car.
16 = (1/9)r^2
r^2 = 16/9
r = 4/3 mph  = 1 1/3 mph
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(c.) Use a calculator to solve part (b) 
numerically. Do your answers agree?
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Cheers,
Stan H.

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