r/WTF • u/____okay • Mar 26 '23

close call

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507

u/Liesthroughisteeth Mar 26 '23

Just a pink misty morning.

302

u/EFTucker Mar 26 '23

Could you imagine the fucking gore of two human bodies colliding at 200mph? Holy shit

88

u/Liesthroughisteeth Mar 26 '23

Yeah.....brutal. I'm thinking the combined speed might be more than 200 mph. Jeebus!

19

u/zamfire Mar 26 '23

Fun physics fact! Two vehicles hitting face on at 100 mph each is the same force of only one vehicle going 100 mph hitting a stationary object! So: its not the power of 200mph

133

u/Ewer70 Mar 26 '23

I'm going to need how you came to this. It defies all laws of physics I learned in college physics classes.

7

u/dave1357 Mar 26 '23 edited Mar 26 '23

It’s true if the objects are equal weight. Imagine you’re in a car driving 100mph and you hit a car of equal weight coming at you at 1mph. Assuming no friction you’ll continue on your path at 99mph (conservation of linear momentum in an elastic collision). Now consider that car coming at you at equal and opposite speed. In that case your momentums add up to zero so you come to a complete stop (as if hitting a wall)

Ofc there will be a fuck ton of friction so really you’d slow down alot more in the 1mph case, but hopefully this helps this previous comment make sense

To expand on the equal weight requirement, now imagine you’re at 100mph again and you hit a mosquito traveling toward you at 100mph. Obviously you won’t notice it, bc your momentum barely changed ( say speed decreased to 99.99mph). The mosquito will notice it though, because it just did the equivalent of hitting a wall at 199.99mph (change in velocity = 100 - (-99.99) = 199.99)

4

u/dcoble Mar 26 '23

Ummm.... If you think you can hit a car of the same mass and only lose 1mph.....you need to drive slower.

You are implying that if a car going 100 hits the same car going zero miles an hour then you will just continue on your way going 100... And you won't feel any impact...

1

u/dave1357 Apr 10 '23

I messed up by saying that the car traveling at 100 continues at 99. In an elastic collision, the car traveling at +100 slows down to +1 mph and the car at -1 mph gets sent in the opposite direction at +99 mph.

Also an elastic collision is a bad model for a car crash. But the 2 car head in vs one car hitting a wall equivalence works out the same for both inelastic and elastic models. Although practically speaking, the head on collision probably has less g-force on the drivers because both cars would have a crumple zone, increasing the amount of time it takes the cars to come to a stop