It is generally accepted that a heavy truck can't stop in the same distance that a car can stop. But from the perspective of basic physics, I don't see why this should be true.
If the truck's mass is 30 times that of a car, then its tires are pressed against the road surface with 30 times as much force.
And that force times the coefficient of friction gives the maximum amount of stopping force that can be applied, which is also 30 times as great as the maximum stopping force of the car.
And by applying 30 times as much stopping force to a mass 30 times as great, the truck's maximum deceleration should be exactly equal to the car's deceleration.
So why do trucks (supposedly) need more space to stop?
Is it that they can't achieve this theoretical maximum rate of deceleration? (They do, after all, have more moving parts?)
Or is it that they are harder to control at maximum deceleration, so drivers are reluctant to do a maximum stop?
Or is it just an old wives' tale to make us cautious?
2007-05-13
16:35:23
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12 answers
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asked by
actuator
5
in
Engineering