Eraser Movie Scene

            This week we watched “Eraser” which in my opinion, suffered in comparison to Mission Impossible III. Eraser failed across the board in cinematic categories such as acting, screenwriting, and of course, accurate portrayal of scientific principles; more specifically, physics. In one of the last scenes of the movie; an epic battle with futuristic weapons takes place on the docs of the Baltimore Harbor. Arnold Schwarzenegger, also known as “The Eraser” is seen firing two weapons that shoot a projectile “close” to the speed of light. For a moment let’s suspend our disbelief that any such weapon would even exist and just focus on the physics.

            The problem that we are investigating is, if the henchmen that Schwarzenegger shoots go flying backwards, shouldn’t he too go flying backwards from the recoil of the gun?

            Since we know the projectile is traveling “close” to the speed of light, we can estimate that as being 3.0x10^7 meters per second. Since they don’t tell us how much the aluminum rounds weigh, I estimated it as 1 gram, or 0.001 kilograms per round. Beyond that, the only things we have to know for the problem are the weight of Schwarzenegger and the weight of the henchmen. After a quick Internet search, I found out that Arnold was roughly 115 kilograms in the movie, and I estimate that the average henchmen is around 65 kilograms. Knowing all of this, we can use conservation of momentum to find out what really should have happened in that scene.

            After performing the calculations, I found that if Schwarzenegger actually fired both rail guns at the exact same time, he would have been launched backwards at a velocity of over 413.8 meters per second. In addition, the henchmen that were shot would have been launched backwards at a rate of 461.5 meters per second. That kind of acceleration would be fatal for anyone, even the Eraser proving that physics is clearly not a required course for anyone intending to major in film related studies.