Distance traveled once the brakes are pushed until the car stops
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d_{b} = distance traveled when the brake was pushed, and the car comes to a stop [m] Note: 1 m ~ 3.3 ft
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Expression 16: "d" Subscript, "b" , Baseline equals StartFraction, "v" squared Over 2 times 9.8 left parenthesis, "m" Subscript, "F" , Baseline cos left parenthesis, StartNestedFraction, "s" pi NestedOver 180 , EndNestedFraction , right parenthesis plus sin left parenthesis, StartNestedFraction, "s" pi NestedOver 180 , EndNestedFraction , right parenthesis , right parenthesis , EndFraction equals 55.5 9 4 6 0 4 4 5 2 2db=v22·9.8mFcossπ180+sinsπ180
equals=
55.5 9 4 6 0 4 4 5 2 255.5946044522
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NOTE: Negative d_{b} values mean the car won't stop by braking under these road conditions (not enough friction can be generated) and the slope of the road.
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Plot the distance while braking with a thick red line
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Expression 19: "y" equals "x" tangent left parenthesis, StartFraction, "s" pi Over 180 , EndFraction , right parenthesis left brace, "d" Subscript, "r" , Baseline cos left parenthesis, StartFraction, "s" pi Over 180 , EndFraction , right parenthesis less than or equal to "x" less than or equal to left parenthesis, "d" Subscript, "b" , Baseline plus "d" Subscript, "r" , Baseline , right parenthesis cos left parenthesis, StartFraction, "s" pi Over 180 , EndFraction , right parenthesis , right brace Has graph. To audio trace, press ALT+T.y=xtansπ180drcossπ180≤x≤db+drcossπ180
The coefficient of static friction is 0.7 for dry roads and 0.4 for wet roads. The tread design represents an "all weather" compromise. If you were an Indianapolis race driver, you would use "slick" racing tires with no tread. On dry surfaces you might get as high as 0.9 as a coefficient of friction, but driving them on wet roads would be dangerous since the wet road coefficient might be as low as 0.1. http://hyperphysics.phy-astr.gsu.edu/hbase/Mechanics/frictire.html#c1
