I’m sure you all have cable and/or satellite setups and thus see the Mythbusters, which is clearly one of the best things on TV, as they produce them. But I am always a couple of years behind because I watch them on Netflix. Two more seasons were released on Netflix very recently, so I’ve been watching them, and I thought one of the Myths addressed was worth bringing up.
Here’s the Myth: If a car is going 50 miles an hour and hits an immovable concrete wall, it suffers a certain amount of damage. If, however, the car hits head on another similar car moving in the opposite direction, then that is like hitting the wall at 100 miles per hour. This belief is widespread, and it makes sense at first. Yet, it is wrong. Having said that, it is actually correct, and when the Mythbusters busted the Myth they may have not noticed that they just busted a perfectly good Myth, and they actually confirmed it while they busted it. In a way.
The myth was tested first by using a scale model. The scale model involved pistons cleverly rigged up with cylinders of mush-able clay. Here was the experimental protocol and results:
1) A pendulum of a fixed weight rigged with mush-able clay is dropped from height A against an immovable object. The clay gets mushed to P% of it’s original thickness.
2) The same pendulum rigged the same way is dropped from height B where (B=2A). The clay gets mushed to 2P% of its original thickness. This simulates the effects of a 50 mile per hour and a 100 mile per hour collision with a fixed concrete wall, respectively.
3) The same pendulum is matched up to an identical opposing pendulum. They are dropped simultaneously from height A. The clay cylinders are found to mush down to P%, not 3P%. Myth busted in scale model.
Then, of course, they do it with cars.
1) A car is driven at 50 mph against a solid wall. It gets mushed.
2) A second car is driven at 100 mph against the wall. It gets much more mushed.
Here are the two cars, the red one was driven at 50 mph, the yellow one at 100 mph:
3) Two cars are then driven at each other at 50 mph, head-on. They are both mushed the same as the red car shown above. Neither car seems to experience a “100 mph” collision.
So, the myth is busted in full scale with the actual objects that the myth is about (cars).
But hold on a second, not so fast. The following two things are also true:
1) With the clay, when two pistons were used, there was sufficient energy to mush two lumps of clay down to the A-height amount, not just one.
2) With the cars, two cars each suffered the effects of a 50 mph collision.
Once you either run this all through in your head, or watch the episode, if you previously thought that a pair of cars hitting each other head on at 50 mph would cause one of them to experience a 100 mph collision, then you will absolutely change your mind. But, if you now think that two cars running into each other at 50 mph each is the same as one car running into a concrete wall at 50 mph, then you’ve got that wrong. Because, when in the end, you’ve got two recked cars not one, and the energy used to wreck each of those cars as per a 50 mph collision is twice the energy it would have taken to wreck one of them.
So it is like a 100 mph collision, shared evenly by two cars (so each gets 50 mph worth!)
The show in question is Netflix Season 8 Episode 2, “Mythssion Control” subtitle Hyneman vs. Newton. The numbering, arrangement, and possibly editing of Mythbusters shows on Netflix seems to be different from that aired on TV.