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 MythBusters - Crash Force - awesome test
#996499
05/10/10 07:10 PM
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Joined: Feb 2010
Posts: 7
OP
Need a Spot
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Video - MythBusters - Crash Force Mythbusters crew decided to revisit an old myth that was drawing the ire of the show's fans for quite some time. And it's sure to be an interesting topic to automotive enthusiasts. When two cars collide, each traveling 50 miles per hour, does the resulting force equal one car hitting an immovable object at 100 miles per hour? It seems like such simple physics, no? But don't forget Newton's third law. To quote the great Wikipedia of knowledge, "Whenever a first body exerts a force F on a second body, the second body exerts a force −F on the first body. F and −F are equal in magnitude and opposite in direction." Or, more simply, for every action there is an equal and opposite reaction.
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 Re: MythBusters - Crash Force - awesome test
[Re: trev0006]
#996500
05/14/10 02:10 PM
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Joined: Dec 2000
Posts: 6,896
Trail Leader
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I like the way that Dae-Woo folded in half in the 100mph crash. Instant death.
I just want to tell you both good luck, and we're all counting on you.
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Re: MythBusters - Crash Force - awesome test
[Re: sparkem]
#996501
05/14/10 04:14 PM
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Joined: Mar 2006
Posts: 6,950
Trail Leader
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One problem with their test......Steel plates don't have crumple zones. They should have crashed into a secured parked car at 100MPH and compared that damage to two cars hitting each other. Comparing two cars head on to a immobile steel plate is inaccurate testing. Fun to watch though. <img src="/forums/images/graemlins/smile.gif" alt="" />
Last edited by cmonty72; 05/14/10 04:17 PM.
96 Montero LS 24V DOHC 3.0L.
98 Montero 24v SOHC 3.5L, factory rear locker, Winter/tow package.
63 Jaguar XKE 3.8L FHC
2000 Mercedes-Benz e430
07 fj cruiser
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Re: MythBusters - Crash Force - awesome test
[Re: cmonty72]
#996502
05/14/10 05:52 PM
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Joined: Feb 2004
Posts: 10,238
Web Wheeler
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I don't think the test was inaccurate - but I don't think it was explained correctly.
When the cars hit the unyielding steel plate, the cars absorbed the energy. At 100mph, the car absorbed twice the amount as it did at 50mph.
When the 2 cars collided at 50mph each, the force was equal to the single car at 100mph, but each car absorbed 50% of the force.
Frank
'89 [color:"white"]G-Raider[color:"white"] [color:"black"]Supercharged 3.0L, MegaSquirt 2, lockup A/T, 2.5" exhaust, 172k, Cibie H4s/Oscar SCs, Hella Micro DE fogs, Cobra CB, Superwinch hubs, LSD rear/Aussie Locker front, Bilsteins, Lifeline AGM, Rust-Oleum
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Re: MythBusters - Crash Force - awesome test
[Re: FrankR]
#996503
05/14/10 06:21 PM
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Joined: Feb 2003
Posts: 2,243
Kia Moderator
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I don't think the test was inaccurate - but I don't think it was explained correctly.
When the cars hit the unyielding steel plate, the cars absorbed the energy. At 100mph, the car absorbed twice the amount as it did at 50mph.
When the 2 cars collided at 50mph each, the force was equal to the single car at 100mph, but each car absorbed 50% of the force.
Frank It doesn't allow the cocoon of the safety cell designed into the monocoque body to take the stresses and the crumple zones to absorb the impacts as it would in a like-for-like crash. Long acknowledged deficit of the crash tests. Reason they have gone for the steel cube is that it is repeatable and fair, not that it is accurate.
2002 Sporty , Ironman 2.5" spring, 2" body, 15 x 7 ROH wheels, K&N, 15 x 10.5 Simex Centipedes, Powerchip 91.
"Never argue with an idiot. They will bring you down to their level then beat you with experience!"
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Re: MythBusters - Crash Force - awesome test
[Re: DamKia]
#996504
05/14/10 06:53 PM
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Joined: Mar 2006
Posts: 6,950
Trail Leader
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When the 2 cars collided at 50mph each, the force was equal to the single car at 100mph, but each car absorbed 50% of the force. <img src="/forums/images/graemlins/kewl.gif" alt="" /> Thats what I'm thinking.
96 Montero LS 24V DOHC 3.0L.
98 Montero 24v SOHC 3.5L, factory rear locker, Winter/tow package.
63 Jaguar XKE 3.8L FHC
2000 Mercedes-Benz e430
07 fj cruiser
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Re: MythBusters - Crash Force - awesome test
[Re: FrankR]
#996505
05/14/10 08:34 PM
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Joined: Sep 2001
Posts: 8,557
Forum Moderator
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I don't think the test was inaccurate - but I don't think it was explained correctly.
When the cars hit the unyielding steel plate, the cars absorbed the energy. At 100mph, the car absorbed twice the amount as it did at 50mph.
When the 2 cars collided at 50mph each, the force was equal to the single car at 100mph, but each car absorbed 50% of the force.
Frank Frank.. this is what I deduced in my brain cells as well. BUT... you have to understand.. this is TV for the public...
87 Raider 4D56td v5MT1
31's..Basically Stock
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Re: MythBusters - Crash Force - awesome test
[Re: LandRaider]
#996506
05/14/10 08:52 PM
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Joined: Feb 2004
Posts: 10,238
Web Wheeler
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The fellow reminded me of myself sometimes - I know I'm right, but when I look at the results, I just can't understand how I am. <img src="/forums/images/graemlins/lol.gif" alt="" />
Frank
'89 [color:"white"]G-Raider[color:"white"] [color:"black"]Supercharged 3.0L, MegaSquirt 2, lockup A/T, 2.5" exhaust, 172k, Cibie H4s/Oscar SCs, Hella Micro DE fogs, Cobra CB, Superwinch hubs, LSD rear/Aussie Locker front, Bilsteins, Lifeline AGM, Rust-Oleum
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Re: MythBusters - Crash Force - awesome test
[Re: FrankR]
#996507
05/15/10 01:50 AM
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Joined: Jan 2001
Posts: 13,649
Web Wheeler
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Doesn't f=mv^2 apply here, making a 100mph solo crash twice the total force of a 50mph dual crash?
Not responsible for advice not taken...
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Re: MythBusters - Crash Force - awesome test
[Re: fasteddy]
#996508
05/15/10 10:07 PM
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Joined: Feb 2004
Posts: 10,238
Web Wheeler
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Dunno - but it would seem to me that an immovable object doesn't absorb any of the force of impact - I would think that all of that force went into the single car. I lifted this from "Ask the Physicist": QUESTION:
if two cars are coming at each other at the speed of 50mph. Is it equal to one car heading at a concrete wall at 100mph?
ANSWER:
It depends a lot on the details of the collisions, but likely the car hitting the wall would be more damaged. Consider one possible case, a perfectly inelastic collision (one where the objects are stuck together after the collision). Also, let's assume the two cars have the same mass M. Further, let's assume that both collisions occur in the same time T (from when the car first contacts until it comes to rest). And, to generalize, let us let 50 mph=V so 100 mph=2V. When the car hits the wall, its momentum (mass times velocity) changes by 2MV; when the car hits the other car, its momentum changes by MV. Finally, what is the physics? One statement of Newton's second law is that rate of change of momentum equals force. So for hitting the wall, the force the car experiences is Fwall=2MV/T; for hitting the other car, the force is Fcar=MV/T. So, the force experienced by the car is twice as big when hitting the wall. (Don't forget the assumptions I have made in reaching this conclusion.) You're correct that the formula applies to determine F, but it still appears to me that the question and answer are confused. The energy released by the 2 cars colliding would seem to be the same total as the single car hitting the wall at 100mph, but the amount of energy is divided by the 2 cars. The way the Mythbusters guy (and the questioner in the above quote) posed the statement seemed to be that either car would experience the same results as a single car hitting a wall at 100mph...... and that's certainly not true.... as we saw. Anyway, I reserve my right to be wrong. <img src="/forums/images/graemlins/lol.gif" alt="" /> Frank
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