@woodrow

The clip they showed was of the two trucks hitting the compact, not just two trucks hitting one another. So, Jamie said it about THAT situation (two trucks, one car), and not about just two trucks. He was right.

The statement

quote:

two cars colliding at 50 mph in different directions is the same as a car hitting a wall at 100mph

is wrong. If the statement was to be correct it should be :

quote:

two cars colliding at 50 mph in different directions is the same as on car travelling at 100 mph hitting a stationary car

. The only problem with Jamie's initial statement is that the changed the type of impact. This has to do with the fact that in the car-wall impact, only the car can give way, but in the car-car impact both cars deform. I was expecting to see Jamie use reference frames to explain the physics, and correct himself to talk about the same objects involved in the two crashes.

I would like to see more science in your shows, the physics would have helped on this one.

I was disappointed!

They ended this by crashing two cars into each other at 50 miles per hour.

Nice...but... I was waiting for them to crash two cars into each other at 100 miles per hour!

I thought you guys were into REALLY wrecking stuff?

Also curious to see a wreck between one car at 50 MPH and the other at 100 MPH. What about adding Mr. & Mrs. Buster and family as passengers? Use those color tab package accelerometers to determine injuries.

Bill the Dog Walker
Staten Island, NY

quote:

Originally posted by ghenderson:
The statement

quote:

two cars colliding at 50 mph in different directions is the same as a car hitting a wall at 100mph

is wrong. If the statement was to be correct it should be :

quote:

two cars colliding at 50 mph in different directions is the same as on car travelling at 100 mph hitting a stationary car

. The only problem with Jamie's initial statement is that the changed the type of impact. This has to do with the fact that in the car-wall impact, only the car can give way, but in the car-car impact both cars deform. I was expecting to see Jamie use reference frames to explain the physics, and correct himself to talk about the same objects involved in the two crashes.

I would like to see more science in your shows, the physics would have helped on this one.

Sorry, but you are completely wrong.

You can prove this with a set of Isaac Newton's clack-clack balls.

You've seen this in novelty stores. Maybe six steel marbles suspended on a frame by two fishing line strings. If you raise one ball ans allow it to swing into the others (one speed (one mass at one speed) it will cause exactly one ball to fly off the other end.

Two ball will cause two balls to fly off.

clack, clack, clack, clack...

Isaac Newton's proof that one mass at one speed imparts its momentum to the group, causing one mass at one speed to fly off.

In a real world collision between large objects there will be "plastic deformation" of the objects. (Metal will bend & crumple, disipating some of the energy.)

In this case, one car at 50 mph hits a wall - it imparts its momentum to the wall and plastically deforms. The wall, being much stronger, does not move or deform.

One car at 100 mph hits the wall and it has much more momentum (the formula was given on the show) causing the car to deform much more.

When two cars crash into each other at 50 mph, each transfers its momentum (one mass at one speed) to the other car. Each car deforms as if it had hit a brick wall at 50 mph. But not perefectly, since the cars can't hit each other as perfectly as they hit a wall, and each car is "plastically deforming" during the accident, which disapates some of the energy. But MythBusters proved the result, to each car, is pretty close to the same car hitting a wall at 50 mph.

Two cars hitting each other at 50 mpg is NOT the same as one car hitting the wall at 100 mph. PROVED by Isaac Newton and MythBusters.

Bill the Dog Walker
Staten Island, NY

quote:

Originally posted by billthedogwalker:
I was disappointed!

They ended this by crashing two cars into each other at 50 miles per hour.

Nice...but... I was waiting for them to crash two cars into each other at 100 miles per hour!

I thought you guys were into REALLY wrecking stuff?

Also curious to see a wreck between one car at 50 MPH and the other at 100 MPH. What about adding Mr. & Mrs. Buster and family as passengers? Use those color tab package accelerometers to determine injuries.

Bill the Dog Walker
Staten Island, NY

PS: Or how about one 2000 pound car at 50 mph versus one 8000 pound SUV at 50 mph?

Bill the Dog Walker
Staten Island, NY

PPSS: There are ENDLESS permutations for wrecking stuff!

Bill the Dog Walker
Staten island, NY

They could only go as far as they could since they'd hit the drivetrain. That's why the 100mph test crumpled into a triangle and flipped. Anything more would result in a bigger "flip" although less crumpling, would make a longer ramp shape.

Am I wrong? Wasn't twice the damage done since each car looked like the ONE car at 50MPH? Isn't that twice the damage and therefor the original statement was correct?

quote:

Originally posted by tomgreen99:
They could only go as far as they could since they'd hit the drivetrain. That's why the 100mph test crumpled into a triangle and flipped. Anything more would result in a bigger "flip" although less crumpling, would make a longer ramp shape.

I think the cars were front wheel drive, and even if they weren't, the drive train starts at the engine. You will notice in the video that damage certainly did not stop at the front of the engine. Once the damage extended past the crumple zones the car became more difficult to crush (as designed). However, the 100mph crash was more than enough to crush the driver compartment (past the end of the drive train in a front wheel drive car).

I still contend that Jamie was wrong regardless how it is phrased. From the perspective of a car being crushed in the middle, or from the perspective of the driver of one of the cars, the 100mph crash into a wall is NOT equivalent to a head on collision at 50mph no matter how it is phrased.

Again, Jamie wasn't wrong. The clip they show when he says that is of two trucks hitting one car. Both trucks hitting the car at 50mph would be the same as one truck hitting a car against a wall at 100mph, approximately.

The clay should have been placed on the end of one car, not in the middle of both.

Everyone knows that the energy would be split between the two cars, but that's not the point. The point is the two trucks hitting one car at 50 would be like one truck hitting the car at 100. The splitting effect doesn't come into play. It's an adding effect.

quote:

Originally posted by Mysta02:
Again, Jamie wasn't wrong. The clip they show when he says that is of two trucks hitting one car. Both trucks hitting the car at 50mph would be the same as one truck hitting a car against a wall at 100mph, approximately.

The clay should have been placed on the end of one car, not in the middle of both.

Everyone knows that the energy would be split between the two cars, but that's not the point. The point is the two trucks hitting one car at 50 would be like one truck hitting the car at 100. The splitting effect doesn't come into play. It's an adding effect.

Ok, if you explain where the extra energy goes then I will believe you.

Scenario:
car 1:
m = 1kg
v = 10m/s

car 2:
m = 1kg
v = -10m/s

car 3:
m = 1kg
v = 20m/s

System 1 = car 1 and car 2.
Kinetic Energy car1 = .5(1kg)(10m/s)^2
= 50J

Kinetic Energy car2 = .5(1kg)(-10m/s)^2
= 50J

Sum = 100J

System 2 = car 3
Kinetic Energy = .5(1kg)(20m/s)^2
= 200J

Thus 100J versus 200J. Where does the extra 100J of energy go in the 2x velocity scenario?

quote:

Originally posted by Mysta02:
The point is the two trucks hitting one car at 50 would be like one truck hitting the car at 100. The splitting effect doesn't come into play. It's an adding effect.

No. It is far more complicated than that.

One car being compacted between wall and 100mph truck would be a LOT worse off than between two 50mph car.

Without the wall, one 100mph truck would do a lot LESS damage than a pair of 50mph trucks working against each other.

Any way you twist it, 100mph truck is just not the same as two 50mph trucks in any configuration.

Ok, so I don't know the math involved, but the point I was trying to make is that they went about disproving Jamie the wrong way. They attempted to disprove his statement by ramming two cars into each other. That's not what he was talking about though. They should have done all their experiments with a 'vehicle' in the middle. That was my point.

Sorry for the math. I'd like to see the math put to the test on Mythbusters for the real experiment.

Jamie's statement was specifically about collisions. He directly stated that impact of two cars at 50 is equivalent to impact of a car at 100 into a wall. He didn't say anything about a 3rd body involved.

But even that aside, he's wrong in either scenario. So you have absolutely no argument.

Actually, I do have an argument. The clip that they showed, and the experiment they were testing in the original episode, was crushing a compact between two trucks. Anything said in that episode has to be applied to THAT scenario.

So, whatever the math is, he is wrong, but for a different reason. And, they should have tested his reasoning against the two-truck-one-car situation.

THAT'S my argument. And, a fair one.

To the observer the impact would be a 100 miles an hour; however the damage is spread across two cars. from the perspective inside either car it is 50 miles an hour. So a small car sitting in the middle is like the observer and would receive twice the pressure.

Thank you

Protyle.

The mistake was made when Jamie admitted he was wrong. Jamie was right with his original statement, the fans were wrong and newton's third law is still valid. The original myth was about the car IN BETWEEN the two trucks. The car in between the two trucks absorbed the mass of truck A traveling at 50MPH and the mass of truck B traveling at 50MPH which IS the equivalent of the car absorbing the mass of one truck traveling at 100 MPH. Newton's third law, a force of 50 + a force of 50 = a force of 100. If you look at the cars, the car between the trucks in the original episode looks a lot closer to the 100MPH car than the 50MPH car. Jamie was right, Newton was right and the viewers were wrong.

Dear Jamie and Adam (or who's representative)

Don't theorize much. Just make your nice and clear hammers test again with one hammer twice as mass as another. And you will see the Jamie's words happen - the force as at 100 mph and the damage as at 100 mph

ma = F = ma

quote:

The mistake was made when Jamie admitted he was wrong. Jamie was right with his original statement, the fans were wrong and newton's third law is still valid. The original myth was about the car IN BETWEEN the two trucks. The car in between the two trucks absorbed the mass of truck A traveling at 50MPH and the mass of truck B traveling at 50MPH which IS the equivalent of the car absorbing the mass of one truck traveling at 100 MPH. Newton's third law, a force of 50 + a force of 50 = a force of 100. If you look at the cars, the car between the trucks in the original episode looks a lot closer to the 100MPH car than the 50MPH car. Jamie was right, Newton was right and the viewers were wrong.

Sorry but no. Force is not the only thing that determines damage. In order to deform something you need a certain amount of energy. Now you are somewhat on the right track with the force thing. The two trucks at 50mph have the same momentum as one truck at 100mph. This means if the two trucks stop in the same amount of time as the one truck does they all produce the same forces. However, it's the kinetic energy that determines the damage done. In that case two trucks at 50mph have the same energy as one truck at about 70.7mph. Now there are a lot of other things that determine exactly what amount of damage is done. You can't just compare speeds you need to use the proper equations at least.

quote:

ma = F = ma

You do realize that equations doesn't apply to this case because the accelerations of a car hitting a car are different than a car hitting a wall. Aside from that this situation clearly calls for an energy based analysis and not a forced based analysis.