Friday, September 11, 2015

Arnold... There is No Way

The 90's were chock full of classic action movies and Eraser is sort of one of those.  Big name action star, female co-star, multiple action scenes, minimal plot, cheesy one-liners, it's all here.  Another thing that Eraser stays true to is the undoubtedly broken movie physics.  The scene I am analyzing happens at the movie's climax, the bad guys have just brought down the warehouse that Arnold was hiding out in, thanks to his quick thinking he tosses his gun to a nearby enemy.  The fool picks it up and is then targeted by his own teammate who mistakes him for Arnold.  The bad guy fires at his comrade as he screams "NOOOOO", he is then struck by the aluminum round and sent flying to the far wall of the remaining warehouse.  Right away you can tell there is seriously something fishy about the physics in this scene, an EM gun firing aluminum rounds at nearly light-speed having virtually no recoil?  As said in an earlier scene, the gun fires rounds at nearly light-speed so let's just assume it is at light-speed. The aluminum rounds seemed to the size of a 50. caliber round, take into account its less massive element I estimated that the rounds would weigh as much as two empty cans or 0.026 kg.  As for the shooter and victim I used the average mass of a North American male so about 80.7 kg.  The gun itself looked like a sniper rifle so I took the average mass of a military sniper rifle so about 12.9 kg.  Add the mass of the gun to the mass of the shooter and you get the shooter's final mass at 93.6 kg.  Finally the velocity at which the round would be going 299,792 km/s or the speed of light.  Taking all this into account I have written out and solved the following momentum equations accounting for the shooter and the victim to see if momentum was, in fact, conserved.
    As you can see, momentum was definitely not conserved in this scene, let alone any in this film where an EM gun was being used.  According to the math and physics behind it, the shooter and the victims would have flown back much farther and faster than portrayed in the film and shooter would not have been able to fire a round off with no recoil at all.  This film is, in fact, scientifically broken. As instructed by Dr. Fragile we were to assume that the round stayed inside of the victim, carrying him off but if we look at the scenes in a different way we can see that this would be impossible.  The rounds traveling at this speed pass through walls with virtually no resistance, this would be the same with the human body but instead the round gets stuck inside them somehow.

1 comment:

  1. Nice entry. One mistake, though. You need to remember to divide by the mass of the victim AND the bullet at the end. Remember, the bullet lodged in the victim when he was hit. It's a small factor, but I want to be sure you know how to do these problems correctly. Of course, you're correct that a bullet traveling at near the speed of light would pass right through a human body without even slowing noticeably. But then the victim wouldn't go flying back as dramatically.

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