Determining the force of impact of two cars...

[Silverwind]

Me and a friend are hot in debate over the force of impact resulting from two objects colliding at different speeds.

Supposing a blue car travelling at 100mph collides with a red car travelling at 50mph, what are the forces of impact for both cars? Both of us agree that the force of impact would be 50mph if both cars were traveling at 50mph, but what about 100 and 75?

[Gan]

25 in the blue car's direction.


-Gan

[Silverwind]

Whoops, I meant to say 100 against 50, not 100 against 75. That answers my question though, and I win the debate!

[EqwanoX]

what? it would be 150mph for each car

[Gan]

 
That's a crazy number, how'd you get that?


-Gan

[Silverwind]

But if the equation is:

Code: [Select]

blueCarImpactForce = blueCarSpeed - redCarSpeed
redCarImpactForce = redCarSpeed - blueCarSpeed

Then the force of impact for the red car seems to come out as -50mph! :-/

EDIT:

Wait a minute... that can't be the equation, as otherwise two cars traveling at the same speed would result in the impact force of 0mph, as if they hadn't collided at all!

[Gan]

Speed is important, but just as important is direction.
Speed and direction together is called Velocity.

If car A is going 50mph North and car B is going 50mph South and they collide their impact will have an outcome of 0mph. Of course their cars will be flattened, crunched, and have dead passengers...

When trying to figure this out keep direction in mind.


-Gan
P.S. I can give you the real equation though it involves vectors. A vector is a magnitude and direction. Such as 50mph North. It uses trigonometry to find the correct speed and direction outcome of two colliding objects.

[Silverwind]

If car A is going 50mph North and car B is going 50mph South and they collide their impact will have an outcome of 0mph.

But that can't be right, because if a car hits a stationary object at 0mhp (in other words, it doesn't hit a stationary object) it wouldn't receive any damage, yet two cars colliding at 50mph certainly would (assuming the cars are traveling in polar opposite directions in a vacuum).

This sum is giving me a headache...

[Gan]

Take your hands and clap them. Your hands are at a certain speed while traveling towards each other. When they collide clasp your hands with your fingers.
As you'll notice your hands go from a certain speed to 0.
That's exactly how colliding cars act if they crash head on into each other.


-Gan

[Jinxycat]

Silverwind, this is insane! Not only are you driving me crazy by talking nonstop about it but now your driving other people crazy.

I don't think anyone will ever be able to work it out. Test your mind on this instead: Why is a raven like a writing desk?

[Silverwind]

Take your hands and clap them. Your hands are at a certain speed while traveling towards each other. When they collide clasp your hands with your fingers.
As you'll notice your hands go from a certain speed to 0.
That's exactly how colliding cars act if they crash head on into each other.


-Gan

LOL! Funniest answer ever, yet I'm still confused. How can the damage resulting from two cars colliding with an impact force of 0mph match the damage resulting from a single car colliding with a stationary object at 50mph?

Silverwind, this is insane! Not only are you driving me crazy by talking nonstop about it but now your driving other people crazy.

I don't think anyone will ever be able to work it out. Test your mind on this instead: Why is a raven like a writing desk?

They're not!

[Connors]

Silverwind all he said is that after the cars that are both doing 50mph hit and are mangled their total speed will be 0. They will stop moving[/i][/u].
I haven't heard the term impact force but I assume that's how much force the car receives when it first hits and before it changes direction or stops?

PS:

They're not!

I bet theres a way they are.

[Gan]

If the cars crunch into each other and become one then their combined speed will be 0mph. If they don't crunch into each other and just bounce into each other then they will fly in the opposite direction at a speed a little less due to friction.


-Gan

[GMG Mike]

When the cars crunch into each other all of the momentum is used up crushing the steel. The cars will go from 50 mph to 0 mph instantly but that momentum (energy) doesn't just go away, it has to be used up somehow. All of the steel is crushed up, this also releases some heat (have you ever bent some metal back and forth several times to break it, then felt the ends and it was hot?)

[Connors]

Exactly what I was getting at! and hf one was going faster then the wrecked cars would skid in the direction of the faster car.