You are driving in a car. Another car is driving towards you. A head on crash will occur.
Is it safer for you to be moving faster or slower than the other car?
>>7959130
Velocity is relative. You're moving at the same speed as the other car, relative to him, always.
Slower. But this also depends how elastic the crash will be and what car model.
Vw bug vs vw bug or vw bug vs hummer, etc.
Doesn't matter. Say the other car is going 45mph and you manage to slow down to 25mph you will still feel the forces of a 70mph crash which will more than likely be fatal if head on.
Since i can move in reverse, just a lower speed than the other vehicle. A faster velocity would be prefered because his velocity would be in the positive direction.
Faster.
>>7959149
Thanks for answering the question?
Just fucking turn
>>7959239
You are driving down a one lane tunnel
>>7959156
But less likely to be fatal than you driving at 50 and having a 95mph crash.
We are talking about odds.
>>7959256
So you're voting for slow down then?
Never thought about this.
But Newton tells you that both car fronts will experience the same force, which will be a function of relative velocity, masses and elastic behaviours.
But that's only for the cars
You will be damaged by the collision with your seatbelt and airbag. Same thing, it's an elastic body collision. So you want to reduce the relative velocity between you and your own car.
Since your cars new velocity depends on its mass and the collision force, I'd say you would want to sit in the heavyest car ?
Quite decent calculations would actually be fairly easy, any motivated mechanicalfag ?
>>7959259
It depends on which direction you choose to be the positive direction and what reference you choose. It also depends on how bouncy the collision will be. The impulse of the impact matters as much as the opposing velicities.
>>7959130
faster, if you are going fast enough, you will just push the other car out of the way and you will be fine. also you want have to travel as far in your seatbelt when you lose velocity because your net force is greater so the change in velocity for you will be less than if you were going slow.
move faster, because you're gonna die no matter what
>>7959240
>>7959256
Different Poster Here.
Assuming it is a very very tight one lane tunnel, and a collision CANNOT be avoided by turning, should you turn the wheel before collision anyway?
Would colliding into the side of the tunnel put you in a more favorable position or velocity?
Assume that anything that results in the least amount of biological damage is most favorable.
>>7959130
i accelerate so i can fucking end it
>>7959236
That is the answer to the question.
The cars collide with a combined velocity, their speeds are relative so it makes no difference. That's assuming it's a head-on collision. If it's a T-bone or whatever, then who knows.
>>7959130
Faster because if you're going faster you're going to give him more momentum than he gives you, which means you're going to feel less force backwards and so its softer. Similar to a truck hitting a car at equal speed. Truck ain't gonna give no shit
>>7959279
gotta go fast
>>7959302
so you're telling me there is no difference between:
a 5mph car and a 10mph car crash
vs.
a 50mph car and a 10mph car crash?
lazy people of /sci/
So I have modeled a car crash under different conditions : symmetric, one faster than the other, one car heavyer than the other.
The acceleration dealt to the driver is the mesure for the dammage dealt to him.
Who was right : those of you saying both are as hurt regardless of who is faster.
Who was wrong : those of you thinking relativity wasn't a thing anymore.
Also, you might want to sit in the heavyest car.
I'll post results and the model.
Pic related : symmetric crash, mostly serves as a validation for the model. Both drivers are hurt the same.
>>7961185
One car faster than the other : both drivers are hurt the same.
>>7961188
One car heavyer than the other : poor guy is dead, rich guy lives
>>7961192
Pic related is the model I used. I'm not used to modeling plastic behaviour, so pardon the aproximations I made. I adapted the parameters so that cars vould compact by about 1m and seatbelts would strech by about 0.3m.
matlab function : https://my.mixtape.moe/muamab.m
information only matters if it is useful
slower because then this information being used would cause both drivers to go slower
>>7961185
Why do some people think doing an elaborate calculation that assumes relativity is more reliable than just pointing out relativity? It isn't. Quite the reverse.
>>7961237
because it's one thing to be able to understand the consequences of relativity in a no too trivial 4 mass system, but it is another to explain it better than "tha't how it works, believe me". See >>7959276 : it is true that you'll "push the car out of the way" and not make a full stop, but how do you best explain that the acceleration dealt to both drivers (not just the cars) is the same ?
Since I believe calculations and graph speak for themselves, here you go.
Also, I'd enjoy some critique to my modeling and method and so on, does someone have feedback ? In particular about better methods of easily modeling the car front plastic deformation.
>>7961292
The results of your simulation don't matter. If your simulation had given the result that one driver did get hurt more than the other, do you think we'd believe your simulation, or laugh at you for fucking it up?
>>7959395
>so you're telling me there is no difference between:
>a 5mph car and a 10mph car crash vs. a 50mph car and a 10mph car crash?
No, you dumb fuck. He's telling you it makes no difference in which of the two cars you are. A head on collision has the combined speed of both.
Let x be the approaching cars velocity
Your velocity should be -x to avoid collision
>>7959280
I would turn into the tunnel wall right away, to slow me down. To the left (left side driver) so that the force of impact is slightly more to the right, less on the driver's side.
>>7959275
oh so slower or faster?
>>7962118
>run into slow moving tractor
>run into fridge at 0.9c
>same
>>7959130
This actually depends on the mass of the cars as well, and this guy >>7959149
is an idiot.
What you want is to be massive and have the least amount of change in your speed.
If we assume that both cars come to a full stop, then you want to be going slower as now you have defined the boundary conditions, and going slower in this case means less of a speed change.
>>7962689
of course, assuming both cars come to an immediate full stop is a bad assumption.
conservation of momentum is easy enough to calculate (pic related you mongs), and again, you are looking for the smallest delta V as possible as this implies the least amount of accelerative force, which is what kills the crab.
>>7962697
note that here we assume a perfectly inelastic collision, which is not entirely accurate but certainly more accurate than assuming a perfectly elastic collision, which ignores things like crumple zones and drivers flying through the windshield.
>>7962686
>>run into slow moving tractor
> >run into fridge at 0.9c
> >same
Are you huffing glue?
The OP doesn't ask anything about refrigerators, relative mas of vehicles, or anything like that.
>>7959130
>Is it safer for you to be moving faster or slower than the other car?
Notice there's nothing about which vehicle is bigger,, or the total speed of the two cars relative to each other.
The only thing he's asking is "safer if my car is faster? safer if my car slower?"
It's kind of a dumb question, because even if there's some minor difference, it's overall MUCH safer to reduce total relative speed before impact.
So you should ALWAYS hit the brakes before a head-on collision.
Anybody who says "hurr, hit the gas, plow right thru unharmed" is a retard.
I actually knew someone who believed this, and yes, he actually had a learning disability, no joke.
>>7962705
OP is asking, given a set of two different speeds, which one is safest.
You are right that its not enough information, but its not the point that you should hit the breaks, because in this thought experiment you are stuck at a given total impact energy.
>>7962697
>accelerative force, which is what kills the crab.
Assuming seat belts (or better yet, airbags) acceleration isn't what kills the crab, but rather being crushed by the crumpled vehicle.
>>7962708
>because in this thought experiment you are stuck at a given total impact energy.
I'm thinking the point is to determine an appropriate course of action in the real world.
The retard I knew actually said he would hit the gas to save himself in such a situation.
>>7962713
You retard... the magnitude of acceleration is what CAUSES the crumpling and the crushing.
>>7962719
>You retard... the magnitude of acceleration is what CAUSES the crumpling and the crushing.
>I'm a retard... the RELATIVE VELOCITY OF IMPACT is what CAUSES the crumpling and the crushing.
FTFY, you're welcome.
Emergency brake, then put the car in reverse, then roll the fuck out of the car.
If there's no time then skip the second step.
>>7959130
Slower.
Everyone saying that is relative is correct, but they are forgetting that there are THREE objects to consider: your car, the other car, and the road. All else being equal, it's better to have a lower velocity relative to the road. It's much less important than relative to the other car, but it still matters.
>>7962733
You realize that the velocity isnt a force right? And it takes a force to cause deformation in a solid? And that if you look at the change in velocity over time (ie initial and final velocity), you get an acceleration, which when multiplied by the mass involved, gives you a force?
If you are going to call people out, you might want to learn physics first.
the slower youre going the less acceleration you will undergo
>>7962895
> it's better to have a lower velocity relative to the road
It depends on the size and shape of your car and the other car.
>>7962904
What if the person who hits you is going really fast and their car weighs ten times your car?
Read the fucking thread, the correct answer has already been posted.
>>7959156
You are retarded. If you are going 50 mph and hit a car going 50 mph it will be like hitting a wall at 50 mph. the velocities don't just "add up" like that and create a bigger force.
NEW SCENARIO :
The total velocity of the crash will be the same (IE 70mph). Would you want to be driving at 70mph or be at a full standstill? Or would both cars going 35mph (or somewhere in between) be best?
>>7962990
I want to be the one driving at 270 mph and the other guy is backing up at 200
>>7962911
>and their car weighs ten times your car?
>Read the fucking thread,
Read the OP, there's nothing about a more massive vehicle.
You might as well argue airbags vs pre-airbag cars.
Or maybe the other driver is shooting at you.
>>7963017
1.) Mass of the vehicles is a critical variable, not my fault OP is too dumb and left it out.
2.) Cars typically do not weigh the same by any means. Its a valid problem.
3.) It highlights the underlying physics, which 90% of the people in this thread are getting wrong.
CONSERVATION OF MOMENTUM.
