Hi Ralphie, you are absolutely correct when saying: »Braking is a product of weight, speed and coefficient of friction.« - But your next sentence »The weight is immaterial as long as all the brakes are functioning properly.« is just plain wrong!
Sit down in your car alone, accelerate to 40 mph and hit the brake pedal as hard as you can and record the distance your car needs to stop. Then repeat with four passengers and a trunk full of luggage and you will see that the same car at the same speed needs a longer distance to stop, because weight is a factor
Unfortunately, you are wrong about my being wrong. However, your driving instructor was right for a myriad of other reasons.
I circled the part that struck me as weird. That is the definition of coefficient of friction as used in accident construction. Now the coefficient of friction is made up of a ton of factors, including the road surface material, dampness versus dryness if the road and the slope of the road, to a lesser degree and depending on accident type the crown of the road.
As far as your idea to have me drive 40 and hit my brakes. I have done that a multitude of times. Most times faster then measure my skid marks. We use to do that when reconstructing an accident. We knew the weight of our squads. (We had those pesky state owned truck scales to weigh on for free). We would know the exact speed we were going (because of certified speedometers and onboard radar, the state spared no money equipping our cars) then by measuring our skids we would get the coefficient of friction.
However, that method became outdated with the anti-lock brakes. We then went to dragging a Tire (cut into a kind of boat) which weighed 50 pounds (lighter than a 100lbs one and still made the math easy. We took at least 3 test runs weight or car to get a good average coefficient of friction to work back the speeds of each vehicle.
It is a common misconception that more surface area means better braking. It is identical no matter the surface area because of the pounds per inch pressing down on that surface.
( however, what you stated is correct for distributing weight over a larger surface flotation on thin ice or snow)
However, you are not alone in trying to tell me or others I am wrong about this. Many attorneys have tried in court and upon appeal, most have failed.
I spent 30 years investigating accidents, while wearing a pretty maroon uniform. I am pretty sure (99.9992%) I am correct on this.
But I will admit I was wrong to say all dux are evil, I forgot to figure in the super duper crime fighting RalphieDux employed by the CIA and the military.