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It's just physics ... but it is not trivial one-parameter plug-and-chug
physics.
My lab assistant is a retired brake engineer--here is his response:...
Another consideration is the lag time (especially for air brake
vehicles). ... This can take
several seconds.
f you're going at 60 mph (88 fps) considerable
distance can be traveled while the stopping power (brake torque) is
being 'built up'.
Also, there is the practical matter of usable space for the brakes and
drums. The big rigs use 20 to 22.5 inch diameter wheels.
The brakes
have to fit into them. Therefore only so much mass and area for heat
conversion and dissipation will be able to be put into the brakes and
drums and only so much room will be available for the forces to generate
the brake torque.
If the brake engineer uses
sufficiently large forces to stop the heavy truck as fast as a car when
it is fully loaded, the force to stop it when empty or just lightly
loaded will be very difficult to control