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 Kookoo42
Male, 18-29, Europe
 16 Posts
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Monday, October 24, 2011 2:52:38 AM
That's a nice convenient compact car for shopping.
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 Buiadh
Male, 18-29, Europe
6650 Posts
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Sunday, October 23, 2011 1:11:50 AM
Wow that looks mighty painful. |
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 RoboPatton
Male, 30-39, Western US
1952 Posts
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Saturday, October 22, 2011 3:14:17 AM
oooh fat cats with tv shows destroying cars the peoples republic of America could have used! |
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 Skreshavik
Female, 18-29, Western US
1288 Posts
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Friday, October 21, 2011 11:52:14 PM
You know what baffles me? When you see some idiot survive a 100 MPH crash, barely unscathed.
Then you see how badly people are...mangled, for lack of a better term in head-on collisions on highways and interstates, just cruising at around 50-60 MPH. |
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 panda4298
Male, 13-17, Midwest US
107 Posts
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Friday, October 21, 2011 8:48:42 PM
i didnt fully understand that concept until i saw that episode of Mythbusters. so thank you physics! |
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panda4298
Male, 13-17, Midwest US
107 Posts
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Friday, October 21, 2011 8:47:35 PM
no it wouldnt. based on newtons 3rd law, which is that every action has an equal and opposite reaction. so two cars colliding at 120 Mph headon would still be like hitting a non moving wall because of the amount of force they throw forward is equal to what is pushed back. that is why the car stopped after the crash instead of continuing in either direction. 120---> <---120 then <--- 120 120---> |
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 DracObi
Male, 18-29, Eastern US
288 Posts
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Friday, October 21, 2011 6:36:41 PM
well, actually, a car going 120 hitting a wall thats not moving would simulate 2 cars going 60 in a H.O.C. 2 cars goinf 120 each hitting would cause the force impact of 240Mph.
OMG facts |
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 Orchideous
Male, 18-29, Europe
361 Posts
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Friday, October 21, 2011 5:42:04 PM
In theory, obviously head on collisions don't tend to be so clean cut |
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Orchideous
Male, 18-29, Europe
361 Posts
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Friday, October 21, 2011 5:41:05 PM
When a car hits another car head on, both cars come to a full stop in the same way, each car goes from 60mph to 0mph. They explained the reason for the force is the deceleration.
A head on collision between 2 cars would not double the force for each car, rather both cars would experience the force of 0-60 in however many milliseconds.
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 Rick_S
Male, 40-49, Eastern US
2860 Posts
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Friday, October 21, 2011 5:18:15 PM
Everyone's talking about the Mythbusters and the science behind this. When I saw this video I thought about the Mythbusters, too, but about the rocket car sled episode. Where the rocket sled goes into the compact car, and then through it, and there is no compact car left. The front half of this focus was kind of like that. |
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 cyborg
Male, 13-17, Midwest US
2799 Posts
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Friday, October 21, 2011 2:43:46 PM
mythbusters did it |
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 SlothOfDoom
Male, 30-39, Canada
2041 Posts
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Friday, October 21, 2011 1:59:15 PM
@Quackor
You...aren't so smart, are you? For the brain dead, it explains at the start of the video that it replicates two cars hitting one another head on.
Only an idiot can't comprehend the purpose of crash tests, wtf is your life supposed to accomplish? |
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 Quackor
Male, 18-29, S. America
2666 Posts
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Friday, October 21, 2011 1:04:26 PM
only a complete idiot crashes 90 degrees into a wall, wtf are these tests supposed to accomplish |
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 KekS
Male, 18-29, Europe
599 Posts
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Friday, October 21, 2011 12:32:11 PM
vegascartman, HolyGod and everyone else claiming that head-on collision of 2 cars traveling at 60 mph is the same as one car hitting a stationary wall at 120 mph: you are wrong. They even tested that on Mythbusters, when will you learn already?
inb4 MYTHBUSTERS ISN'T REAL SCIENCE, etc. |
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 Fatninja01
Male, 18-29, Australia
23995 Posts
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Friday, October 21, 2011 12:26:36 PM
Yeah,,, they could walk away from that :P |
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 OldOllie
Male, 50-59, Midwest US
8742 Posts
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Friday, October 21, 2011 12:25:59 PM
Uhhhh...anyone else catch the error in their math? If a car hits a wall at 120mph, that DOESN'T mean you are simulating TWO cars hitting head-on at 120mph each, as they suggested in the first few seconds of the video. Each car should be simulated going 60mph hence, the same as 1 car hitting a stationary wall at 120.
Actually, their math is correct. Hitting another car going the same speed is the same as hitting a wall since in either case, your car is stopped cold.
When 2 cars of equal mass collide head-on, you can add the speeds to get the equivalent of hitting a parked car of equal mass. However, a parked car will recoil and absorb half of the energy of the collision. When you hit an immovable object, you absorb ALL the energy. |
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OldOllie
Male, 50-59, Midwest US
8742 Posts
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Friday, October 21, 2011 12:20:29 PM
Forgive the stupid question, but force is equal to mass x acceleration right? So does that mean there is technically no measurable force on the wall because it doesn't change speed? How does that work?
Technically, the wall DOES accelerate. However, since it is effectively part of the earth, the acceleration is imparted to the entire earth. So in your equation F = ma, or F/m = a, if you have a very large m (~6 x 10^24 kg) you end up with a very small a. A quick calculation shows that at the moment of impact, the earth sped up by ~6 x 10^21 m/s
Next time, give me the car, and I'll tell you what would happen. |
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 vegascartman
Male, 30-39, Western US
735 Posts
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Friday, October 21, 2011 12:16:42 PM
Uhhhh...anyone else catch the error in their math? If a car hits a wall at 120mph, that DOESN'T mean you are simulating TWO cars hitting head-on at 120mph each, as they suggested in the first few seconds of the video. Each car should be simulated going 60mph hence, the same as 1 car hitting a stationary wall at 120. |
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OldOllie
Male, 50-59, Midwest US
8742 Posts
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Friday, October 21, 2011 12:12:00 PM
Forgive the stupid question, but force is equal to mass x acceleration right? So does that mean there is technically no measurable force on the wall because it doesn't change speed? How does that work?
Technically, the wall DOES accelerate. However, since it is effectively part of the earth, the acceleration is imparted to the entire earth. So your equation F = ma, or F/m = a, if you have a very large m (~6 x 10^24 kg) you end up with a very small a.
Next time, give me the car, and I'll tell you what would happen. |
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 freddyferret
Male, 40-49, Midwest US
9843 Posts
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Friday, October 21, 2011 11:54:12 AM
At least the back two wheels survived. That's something, right? |
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Angilion
Male, 40-49, Europe
9554 Posts
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Friday, October 21, 2011 11:15:49 AM
Forgive the stupid question, but force is equal to mass x acceleration right? So does that mean there is technically no measurable force on the wall because it doesn't change speed? How does that work?
It's not a stupid question. It's a good question. Here's my take on it:
i) The force on the wall is equal to the force on the object hitting it. Newton's third law. Newtonian physics is an approximation, but at these speeds it's an extremely accurate one.
ii) If the wall is attached securely enough for it to not break, it is in effect part of the Earth. The mass is therefore extremely high, so the acceleration is negligable. |
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 HolyGod
Male, 30-39, Western US
2911 Posts
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Friday, October 21, 2011 11:09:26 AM
Forgive the stupid question, but force is equal to mass x acceleration right? So does that mean there is technically no measurable force on the wall because it doesn't change speed? How does that work?
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 Gerry1of1
Male, 50-59, Western US
25640 Posts
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Friday, October 21, 2011 11:08:49 AM
Angilion, is "The Bing Bang Theory" tv show based on your life? Which one are you?
 |
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SharkFreak
Male, 18-29, Eastern US
65 Posts
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Friday, October 21, 2011 11:04:20 AM
It looks like it only got halfway into platform 9 3/4. |
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 evanbartlett
Male, 30-39, Western US
547 Posts
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Friday, October 21, 2011 10:54:22 AM
The issue of 120/240 all deals with how much force each body absorbs. If a car is travelling at 120 m/s and a wall is travelling at -120 m/s, when they hit, the car receives an impact as if it were travelling 240 m/s. In the case of two identical cars, one travelling 120 m/s and the other travelling -120 m/s, when they impact, they each absorb half of the total force of impact, and so each is damaged as if they hit a wall at 120 m/s. |
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