Question 1080913
D=(1/16)x^2, presumably where x is speed in mph
D=(1/16)*900=56.25 feet
D=(1/16)*4900=306.25 feet
Estimate 20-25 mph for stopping distance of 49 feet
49=(1/16)x^2
784=x^2
x=28 mph.
the quadratic form of the equation makes linear estimation difficult.