Car Crash: Wall vs. Identical Vehicle - Which Does More Damage?

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In summary, the conversation discusses the damage done when a car crashes into a concrete wall at 40 km/h compared to when two identical cars traveling in opposite directions collide at the same speed. While some argue that the damage would be equal, others point out that the relative velocity in the second scenario is double that of the first, resulting in greater damage. However, the quoted website explains that the damage is actually dependent on the relative velocity and not the number of vehicles involved. The conversation also mentions a previous discussion on the topic and suggests doing a Google search for more information.
  • #1
Shane
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okay bringing up an old topic but

a car (lets just say 2000 kg) drives into a concrete wall (essentially immovable) at 40 km/h.
the same vehicle (make and model not the product of the colliision!) drives head on into another identical vehicle traveling in the opposite direction; both at 40 km/h.

Which does more damage?

They are equal no? Argue me if I am wrong but also couldn't you argue that the vehicle crashing into the wall has momentum lost to recoil, rolling away from the wall after it has hit? All of course depending on the construction of the car right? those cars in demolition derbies are built (impracticably for the transfer of momentum and safety's sake) to withstand heavy blows, so couldn't that vehicle lose some momentum to recoil on colliding with the wall?
 
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  • #2
Also quoting this website: http://www.sciam.com/askexpert_question.cfm?articleID=00042194-68C4-1C71-9EB7809EC588F2D7

"You will do less damage to your car and yourself by hitting a fixed object. The reason is that the damage done is a function of the relative velocity of the objects. If you are traveling at 35 miles per hour and hit a large tree, the relative velocity is 35 miles per hour. However, if you hit a car coming toward you at 35 miles per hour, the relative velocity is twice that. The effect of hitting the other car is therefore roughly the same as of driving into the tree at 70 miles per hour."

Is that true? I had an extremely long argument with my physics teacher agreeing with the above quotation, but my physics teacher argued that even though the relative momentum is twice as much, there are two cars and the momentum is transferred as such with each vehicle taking half of the momentum during the crash.
 
  • #3
I swear we had this same thread twice in the last two months. Why don't you do a google search for it? Hell, I did it for you. https://www.physicsforums.com/showthread.php?t=97485 There's one.

Did you read the next two paragraphs of the Scientific American link. The next two said why your quoted explanation was wrong.
 
  • #4
Please do NOT start the same thread again! Respond to the existing thread that you have started already. Multiposting of the same topic is not allowed on PF.

Zz.
 

1. What factors contribute to the amount of damage in a car crash?

The amount of damage in a car crash is influenced by several factors, including the speed of the vehicles, the weight and size of the vehicles, the angle of impact, and the safety features of the vehicles.

2. Is it more dangerous to crash into a wall or an identical vehicle?

It is generally more dangerous to crash into a wall than an identical vehicle. This is because walls are stationary objects and do not absorb any of the impact energy, whereas identical vehicles can absorb some of the energy, reducing the force of impact on the occupants.

3. Can the damage in a car crash be predicted?

The exact amount of damage in a car crash cannot be predicted, as it depends on numerous variables. However, crash tests and computer simulations can provide a general idea of the potential damage in different scenarios.

4. What are some common injuries in a car crash?

Some common injuries in a car crash include whiplash, broken bones, head and neck injuries, and internal organ damage. The severity of these injuries can vary depending on the force of impact and the safety features of the vehicles.

5. How can we reduce the damage in a car crash?

The most effective way to reduce the damage in a car crash is to follow safety precautions such as wearing seatbelts, maintaining a safe speed, and avoiding distractions while driving. Additionally, advancements in vehicle safety technology, such as airbags and crumple zones, can also help reduce the damage in a crash.

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