AVERAGE STOPPING DISTANCES

Two factors are involved with stopping the car: 1) Driver reaction time, and 2) Car braking efficiency. Car weight and velocity are also important considerations in total braking. Here are how the above-named factors enter into overall braking:
Miles Per Hour	20	30	40	50	60	70	80	90
Driver Reaction Time (in feet)1	21	31	41	51	62	72	82	92
Braking Distance (in feet)2	17	39	70	109	156	213	278	360
Total Distance	38	70	111	160	218	285	360	452
1Before a driver's mind and body react to the need for car braking, the car travels this far.
2Even excellent brakes require time to take hold, and this means the car will travel further when the brakes are first applied than it will when maximum braking is achieved.
Weight/Speed Relationship: If weight is doubled, stopping power must be doubled. If speed is doubled, stopping power must be increased four times. If weight and speed are doubled, stopping power must be increased 8 times.

Coefficient of Friction/Temperature/Fade Relationship:

Differently formulated brake lining materials react differently in identical braking/temperature situations, as indicated above. Note that linings with a "cold" coefficient of friction of approximately D.4 behave almost the same up to a temperature of approximately 250°F (121.11°C), thereinafter each lining takes on a different operating characteristic. Only the highest grade linings should be used in every application.