A couple weeks ago i started going to driving school, its boring but neccessary. On the first day she said (the teacher) that a fully loaded transport truck will take LESS time to stop than an empty one. her reasoning for this is the weight of the truck pulls it down and slows it faster. i know this cannot be right becuse the weight of that cargo is going to carry momentum and is going to be harder to stop. My dad has been driving truck for 30+ years and he agrees with me, so im pretty confident with my side of the argument but i need a way to prove it. ive been looking on the net for the past while but the math involved with it is way over my head and i cant find one that involves weight either. Do i need to find the kinetic energy first before i can solve this. i found an equation to find the KE that take speed and weight into factor but i couldnt find an equation that finds braking distance when you know the kinetic energy. if some one knows an equation i could use for this, or some way i can find this out it would be greatly appretiated.

ps: a site supporting my side would work too but if i had the math to back it up she cant really argue with that. and that would really be supperior

thanks alot

phil