bOLsAK=3

bOLsAK=3

This is a bit disturbing.

The metal that has been used to build the JK has always been a concern to me due to it's thin-ish nature. This photo only reinforces those concerns.

Laughingstok

Let's do some math here.

KE = 1/2mv^2

Kinetic Energy (in joules) is equal to one-half the mass of an object (in kilograms) multiplied by the velocity (in meters per second) squared.

The tip of that branch looks to have been about 3 inches in diameter.

This means if you could find the weight of a loaded Rubicon Unlimited JK, and estimate the guy was moving only 2.24 meters per second (5 mph).. then square it.. 5.01 (Lets say 5)

So now we need to know the weight of the vehicle in kilograms. Anyone take a guess?

Let's estimate a conservative 1,000 pounds for the test. 1,000 pounds in kilograms is 455 kg.

So back to equation:

KE = (1/2 * 455) * 5
KE = 227 * 5
KE = 1136 Joules of energy

A joule is the amount of work (energy burned) by a force on one Newton to move an object one meter.
This is about the same amount of energy it takes you to lift a small apple (102 grams) one meter (a little over 3 feet)

Multiply that force by 1136, and then apply it to a 3-inch diameter..

That's how much force was applied to the firewall. (Remember, the weight of the Jeep is unknown as is the speed, but using the estimates of only 1000 pounds for the Jeep and its moving only 5 mph [very unlikely] leads to this answer)

A better example of one joule of energy is about the amount of energy released if a single textbook is dropped one meter.

So stack up 1136 textbooks, smash them into a 3-inch diameter cylinder.. hold it up one meter, and drop it.

Think that'd punch through your firewall?

wayland1985

INTENSE.

Laughingstok

Using that you could figure out just how tough the firewall is.. we'd have to know the exact speed the Jeep was going (impossible) and the weight of the Jeep (possible)

But once we get the weight, we can simply make a scale showing different speeds and just how much energy was being applied to a 3-inch diameter circle on the firewall.

Then you can basically judge just how tough it is.

Laughingstok

A better example of one joule of energy is about the amount of energy released if a single textbook is dropped one meter.

So stack up 1136 textbooks, smash them into a 3-inch diameter cylinder.. hold it up one meter, and drop it.

Think that'd punch through your firewall?

racer83l

Laughingstok, the JK's weigh closer to 4,000 pounds....

Laughingstok

Yeah I saw that the guy said there was a point on it.

And you're right, you would then focus the energy on a much smaller area.

I just kept it simple for the sake of argument.

Laughingstok

Ah wow..

And he had a WARN bumper with winch.. but we'll ignore it and say its a stock Rubicon.. just for simplicity.

Thats 1818 kilograms.

Which means:

KE = (.5 * 1818) * 5
KE = 909 * 5
KE = 4545 joules

So pretend 4545 textbooks (102 grams each) pressed into a 3-inch cylinder and dropped one meter.



Gonna punch a hole without much issue.. and you'd have to have some pretty reinforced armor to stop it. I'd be surprised if even the "older" Jeeps could have withstood it.

Brycer

I bet he didn't have a trail rated badge on it.