Homework 11 Building a Scene

Science Fact or Cinematic Fiction?

Movies are made for the purpose of entertaining its viewers. However, entertainment doesn’t always translate into realistic physical motion, especially in action movies. The scene I chose to analyze for inaccurate physics principles is from 2009’s G.I. Joe: the Rise of Cobra. Three principles that I found violated physical reality in the G.I. Joe movie happen to be Newton’s three laws of forces which include: the law of inertia, the law of acceleration and direction of force, and the action-reaction principle.

The scene is a typical chase scene in which the good guys are chasing the bad guys, with one exception the good guys (the Joes) are on foot and the bad guys (Cobra) are in a vehicle, which one might think would be unfeasible if not for the accelerator suits that the G.I. Joe’s wear that enable them to keep up with the speeding vehicles. The scene takes place on the streets of Paris among the tourists, cars, and trains of the city which makes for a myriad of crashes, collisions, and a ton of action.

Newton’s first of his laws of forces that I will discuss is the principle of inertia. The principle of inertia maintains that an object moves with constant, uniform motion until acted on by an unbalanced force. In the scene being analyzed, this principle is violated in a way that might not be obvious. The violation occurred when Marlon Wayans’ character, Ripcord, jumped through the windows of a train moving at about 35mph. The issue with the scene is that the train continued to move forward during the jump because there was no force acting on the train that would have stopped it or slowed it down, the brakes were never applied. The same continued movement forward should have applied to Ripcord. If these rules had been obeyed the trains movement forward a few feet, should have resulted in Ripcord going through a point of the train not directly across the point of entry, but across and a few feet posterior to the point of entry; perhaps, a different window or through the wall of the train. This is not what happened and Ripcord exited directly across his point of entry despite the continued movement of both himself and the train.

The second of Newton’s law’s that is violated in the movie is the law of acceleration, more specifically, acceleration and direction of force. This principle states that when a force is perpendicular to the path of action of an object, it then deflects the motion of that object into an arc. The point of the scene when this law was not obeyed was when the hummer vehicle that was speeding down the streets of Paris collided with a passenger train. What the audience saw was the train colliding with the hummer at a perpendicular angle, and then the hummer was propelled into the air in the exact same direction (straight) that it was originally travelling; this would not be the effect in the real world. If this scene had taken place in reality the train would have had a rather large impact on the hummer because of its greater mass and speed, which translates into a large force that would have resulted in the derailment of the hummer from its original path of action and propulsion into a diagonal arc. It would have been possible for the hummer to be raised up into the air somewhat because the front of the train was wedged, but not to the degree it flew in the movie and definitely not in a straight and forward motion.

The last one of Newton’s laws of forces that is not correctly applied in this scene is the action-reaction principle. The action-reaction principle asserts that for every action force there is an equal reaction force in the opposite direction. Violation of this principle can be seen numerous times in this scene. One of the most obvious blunders of this principle can be seen with the incredible jumps that the G.I. Joe’s perform with very little effort. One component of the action-reaction principle with regards to jumps states that how high you jump depends on the force and on the distance over which you apply that force. Somehow, the Joe’s were able to jump incredibly large heights with very little effort. The Joe’s applied very little force to the ground on which they were standing and yet, were able to jump roughly 30 feet in the air almost instantaneously. The jump force would have had to be very large to enable something a human’s size to jump as high as 30 feet, and would result in the action of the jump leaving an impression on the ground, but this did not happen in the film.

Another example of the action-reaction principle being ignored in this scene was the use of the enemy weapon; a gun that fires, not bullets, but powerful blue pulses of energy. The problem I had with the scene is not that a handheld gun was shooting pulses, but that the powerful pulses had no kick back and only acted on their target. In reality when someone shoots a gun, the powerful propulsion of the bullet forward has an effect on the person holding the gun, as it should because every action has an equal and opposite reaction. This physical principle is ignored here. What happened when a person shot the weapon was impossible because there was no reaction. Every time the weapon was fired at its target, be it a person, glass, or concrete, destructive force followed, but it was unrealistic because the direction of the force was only forward in motion, flowing out of the gun. If this weapon was an actual weapon the power of it would jolt the user backward, if not completely send the weapon flying out of their hands due to the inability of a person being able to hold on to something so forceful.

The final illustration of the action-reaction principle being violated in this scene, again, involves the hummer vehicle. Throughout the scene the hummer was racing down the streets of Paris, eliminating anything in its path, including other vehicles. When the hummer collided with another car, the hummer seemingly lifted the car and sent it flying over the top of the hummer without fazing the hummer in the slightest. There was not an effect on the speed or exterior of the hummer whatsoever, as if the car was just a leaf blowing by. The hummer was substantially heavier than a regular car, but not so heavy that a 2-ton car would not have an effect on the momentum of it. The action of the hummer on the car would have caused an equal reaction on the hummer in the opposite direction, so the weight of the car should have slowed the hummer and forced the hummer into the ground, again this did not happen.

G.I. Joe: the Rise of Cobra is like any other movie with CGI effects. There are inevitably going to be discrepancies between what’s physically possible in the world of the movie and the real world. Sometimes the discrepancies are intentional, necessary to enhance the entertainment factor of the movie and sometimes they are just oversights that most people don’t even notice. In the scene I’ve just discussed both of these types of discrepancies appear. When the principle of inertia was violated I believe it was an oversight. When the principle of acceleration and direction of force was violated I believe it could have been either an oversight or intentional because the effects artists probably wanted the action to stay in the frame. I believe the violations of the action-reaction principle were intentional and added to the allure and action in the movie. Overall, I’ve come to accept the errors that sometimes appear in movies and somewhat appreciate them for what they are because without them movies, such as G.I. Joe: the Rise of Cobra probably would not have been as entertaining as it was.

Outline of second term paper

I. Introduction
A. Introduce common physics errors in G.I. Joe movie- Newton’s 3 laws of forces
B. Action/Reaction principle violated
C. Acceleration in direction of force
D. Principle of Inertia
E. Set up scene in G.I. Joe-Rise of Cobra


II. Action Reaction

A. For every action force there is an equal reaction force in the opposite direction.
1. How high you jump depends on the force and on the distance over which you apply that force
a. Ex. When the Joe’s jump when they are in their suits. The distance the jump is not congruent with the amount of force exerted on the ground.
2. Ex. When the bad guys shoot the ray/force gun the kick back does not match the force that exerted on the target (glass, concrete, Joe’s).
3. Ex. Hummer maintains a constant speed, despite colliding with vehicles.

III. Acceleration and direction of force.

A. When a force is perpendicular to the path of action then it deflects the motion into an arc.
1. Ex. Hummer traveling along, gets hit with train that is perpendicular, the hummer is deflected into an arc forward, not to the side as it should have been.

IV. Principle of Inertia

A. An object moves with constant, uniform motion until acted on by an unbalanced force.
1. Ex. When one of the Joe’s jumped through a moving train, he should not have hit the train directly across (180˚) from the spot he entered the train.


V. Conclusion

A. Summarize main points
B. Restate thesis statement