Remember your HS Physics?

So the surface area and number of tires, brake pads, rotors, drums, etc play no part in your stopping distance?

smkettner wrote:
therefore the answer is .0023 of 30 = .069165 of a mile,365.19 feet

Here's what the formulas say:

First, find acceleration: (Yes, it must be linear)

a = (v - v0)/t
Where:
v0 = initial velocity
v = final velocity
a = acceleration
t = time
solving: 7.2289156626506 ft/s2

Find distance:
s=0.5 at^2
= 0.5 (7.23 ft/s)(8.3s)^2

7.23 * 68.9 =498.15/2 = 249 ft

aerbus32 wrote:
Me neither. Didn't take it. But have come across something called 'kinetic energy' (energy of movement) that is quantified by the formula K.E. = 1/2 Mass times Velocity Squared. The question often comes up on RV forums about how fast people drive their rigs and disagreements ensue. Just saying . . . Do the math.

And the force your brakes exert is a very complex formula that boild down to Mass times constant.

Thus stopping distance, no matter if you are driving a Mini-Cooer or a 160,000 pound steel hauler.. From the moment the wheels lock up (Note below) is a matter of Speee*Speed/(Coefficient of friction*Constant)

On the ideal REFERENCE surface this means
10 MPY 5.5 feet
20 MPH 22 feet
40 MPH 88 feet

((Speed/10)Squared tunes 5.5)

Of course you will almost never be on the Reference road so your ractual stopping distance may be more or less.

Have posted this several times.

subcamper wrote:
I think the key item to note in the kinetic energy equation is that the energy is related to the SQUARE of the velocity. Which means doubling the speed quadruples (x4) the energy. In order to stop, the brakes have to convert that energy to heat (minus a little frictional loss here and there). Note in car tests what the stopping distances are at 60mph and at 70mph. A common figure at 60mph is 80ft, but at 70mph that often stretches to 140ft. See what a difference 10mph makes in stopping distance?

Also, distance=1/2*(acceleration in feet per second squared)*(time)^2. This assumes starting from rest. So if the acceleration rate is not constant, you can't solve for distance (as noted by smkettner)as there is one equation with two unknowns.

The other important equation is v^2 = 2*(acceleration)*(distance).

With those two equations you can figure out a lot, assuming constant acceleration.

Steve

yes that is the important part of the equation. as speed doubles the kinetic energy goes up by 4 times. should be on every drivers test and their should be simulators like for pilots.

Crowe wrote:
Let's boil it down to simple terms for non-technoweenies like me:

Sure, you can tow it, but can ya STOP it????

Stopping is no problem. As another forum thread is going on, you can always stop your RV, no matter how fast or what kind it is by running into a house! That will stop you for sure! Who needs brakes? ;)

I think the key item to note in the kinetic energy equation is that the energy is related to the SQUARE of the velocity. Which means doubling the speed quadruples (x4) the energy. In order to stop, the brakes have to convert that energy to heat (minus a little frictional loss here and there). Note in car tests what the stopping distances are at 60mph and at 70mph. A common figure at 60mph is 80ft, but at 70mph that often stretches to 140ft. See what a difference 10mph makes in stopping distance?

Also, distance=1/2*(acceleration in feet per second squared)*(time)^2. This assumes starting from rest. So if the acceleration rate is not constant, you can't solve for distance (as noted by smkettner)as there is one equation with two unknowns.

The other important equation is v^2 = 2*(acceleration)*(distance).

With those two equations you can figure out a lot, assuming constant acceleration.

Steve

DutchmenSport wrote:
Well, I had an uncle that always said, "drive fast, love hard, die young, and leave a beautiful memory!"

And I want to die like my uncle - quietly in my sleep. Not screaming in terror like the passengers in his RV.

pconroy328 wrote:

aerbus32 wrote:
The question often comes up on RV forums about how fast people drive their rigs and disagreements ensue. Just saying . . . Do the math.

Wouldn't f = ma be more appropriate?

I prefer E = mc2

This reminds me of one test in the chemistry class, we all had our stations and in front was a wood tray with one test tube that had a clear liquid, the teacher told us to find out what this liquid was, that was the test, at the end of the time, he asked if anyone had identified the substance, none of us had figured it out.

He took the test tube in front of him and drank it, he said it was good water, we performed any number of test to no avail.

I prefer the dormant energy, it is about time for bed, the 11 o'clock news is on and the cat is already snoring.

navegator

HS Physics........then onto NAVY 'A' School followed by Nuclear School
Calculus, Thermodynamics, Nuclear Physics, Chemistry etc.

Makes my head spin to think about it.......now a days I have to count using my fingers :B

If not linear there is no solution with data given.