GMC 1996 Suburban Owner's Manual page 165

-
of a Vehicle
You have three systems that make your vehicle go where
you want it to go. They are the brakes, the steering and
the accelerator. All three systems have to do their work
at the places where the tires meet the road.
Braking
Braking action involves perception time and reaction time.
First, you have to decide to push on the brake pedal.
That's perception tirne. Then you have to bring up your
foot and do
it. That's reaction time.
Sometimes, as when you're driving on snow or ice,
it's
easy
to
ask more of those control systems than the tires
and road can provide. That means you can lose control
of your vehicle.
Average reuctiorz time is about 3/4 of a iecond. But
that's only an average. It might be less with one driver
and as long as two or three seconds or more with
another. Age, physical condition, alertness, coordination
and eyesight all play a part. So do alcohol, drugs and
frustration. But even in 3/4 of a second, a vehicle
moving at 60 mph (100 km/h) travels 66 feet (20 m).
That could be a lot of distance in an emergency, so
keeping enough space between your vehicle and others
is important.
And, of course, actual stopping distances vary greatly
with the surface of the road (whether it's pavement or
gravel); the condition of the road (wet, dry, icy); tire
tread; and the condition of your brakes.
4-5