Science Fact or Cinematic Fiction?

Chinese kung fu movies are uniquely special in their action effects. Many of these action movies poke fun of Newton’s 3^rd law of motion to heighten the effects as well as highlight a characters strength and fortitude. A general example of this technique is a small person who is able to throw a punch with such great force, that it sends a larger person flying away without little or no reaction sent back to the deliverer. The directors and production crew implements this technique to exaggerate specific scenes, making the experience larger than life. Although this technique is usually implemented in kung fu fighting movies, there are examples that poke fun of Newton’s 3^rd law for comedy. Shaolin Soccer, directed by directed by Stephen Chow, is a movie about former Shaolin monks who implement their superhuman fighting techniques in soccer matches. The characters are able to send soccer balls flying at ridiculous speeds, exert large forces on massive objects without any reaction to themselves, and even stop greatly accelerated objects with no recoil at all. Since the action/reaction violation is consistent throughout the movie, it does not seem as far-fetched in the movie’s world. Rather than a violation of Newton’s 3^rd law, this movie pokes fun of the 3^rd law to highlight the comedic value.

Newton’s 3^rd law centers around the equilibrium between action and reaction. This law takes into consideration the force an object exerts on another, the reaction the second object exerts on the deliverer and the masses of both objects to come equate the acceleration that each will undergo. An example would be two people of different mass pushing upon each other; the small person would undergo a larger acceleration than a heavier person, but each would receive the same force. Mathematically, this would work as:

(action force of a small object) = (reaction force of a large object)

([lower mass]/[higher action acceleration]) = ([larger mass/lower reaction acceleration])

Even though the same law is violated within Shaolin Soccer, there are examples where the numbers in the equation are different. Nevertheless, the same law is still being eschewed for our enjoyment.

The first example involves two small masses, one of which produces a very large acceleration on the other, while there is little/no reaction back to the first object. The main character, “Mighty Steel Leg” Sing, kicks a soccer ball high into the atmosphere, with the ball maintaining a vastly long hangtime.

(0:08 – 0:30)

The objects at work in this scene are Sing’s leg exerting force against the soccer ball. (We will assume the mass of Sing’s leg to be relatively small compared to the possible force that it can produce) Although both masses are relatively small, Sing’s leg can produce incredible forces with a decently fast kick but with small amount of reaction back from the ball. To create such a kick in real life, Sing’s kick would need to accelerate at an equally high rate, and the reaction from the ball to the leg would also be just as strong from the leg to the ball. Another way to do this kick is to make the mass of Sing’s leg extremely large with enough acceleration to send a ball into the sky; although the acceleration would not have to be as great as it is on the ball.

(Sing’s leg/acceleration of the kick) = (soccer ball’s mass/acceleration reaction from the kick)

From the movie, the equation is as follows:

(small mass/fast acceleration) = (small mass/incredibly fast reaction acceleration)

Currently, the forces are unbalanced between each other. Sing’s leg is producing large forces from a normal kick without receiving an equal amount of reaction from the ball. To make this scene true, the acceleration and reaction would have to be increased, or mass of the leg would need to increase.

(small mass/incredibly fast acceleration) = (small mass/incredibly large reaction acceleration) or

(very large mass/fast acceleration) = (small mass/incredibly large reaction acceleration)

But the scene breaks Newton’s 3^rd law in order to demonstrate how strong the main character can be. It is also acts as a challenge to Sing, as he would need to control his strength in order to help his teammates in the long term.

Another example within the movie demonstrates how a person of small mass can exert a large amount of force without much effort on an object of larger mass while producing very little reaction. The character and love interest to Sing, Mui, displays an unusual way of parallel parking as she shoves her car into her parking space.

There is a considerably big difference between masses, as Mui’s mass is greatly small compared to a car. Despite the difference, Mui is able to deliver a force so large on the car that she is able to shove it using a normal push. Also, there is little reaction sent back to Mui, as she would either fly back from the recoil or sink into the concrete if she braces herself. The physics equation of this action is as follows:

(Mui’s mass/acceleration of the push) = (car’s mass/reaction acceleration from the push)

(small mass/fast acceleration) = (large mass/fast reaction acceleration)

The equation does not equal out, as Mui would need to greatly increase the force of her push upon the car, or the car’s mass would have to be at most generally equal to Mui’s mass for her to maintain her posture through the push. To make this scene physically true, the equation would need to work out as such:

(small mass/incredibly fast acceleration) = (large mass/fast reaction acceleration), where as Mui’s shove accelerates at superhuman speeds as she takes just as much reaction force from the car, or

(small mass/fast acceleration) = (small mass/fast reaction acceleration), where the car’s mass was originally small or it has magically lost a great percentage of its mass as she pushed it.

This scene shows comedic style because in no way can a small woman shove a as the movie portrays. But this scene ties in throughout the movie as it is another instance of how Newton’s 3^rd law was intentionally broken to make a small character appear grand.

One last example of equal and opposite action/reaction equation is during the final soccer play where the Shaolin soccer players go against a genetically enhanced team. Sing kicks the soccer ball with such force that it causes ripples on the field as the ball flies above, but it is caught by the opposing team’s goalie, Team Evil’s Goalkeeper, with very little reaction acted upon the goalie.

(0:00 – 0:20)

(soccer ball’s mass/incredibly fast acceleration) = (goalie’s mass/little or no reaction acceleration). As seen in the video, the goalie’s posture is unaffected by the force of the soccer ball. It seems the only reaction enacted upon the goalie would be the friction from the ball as his hands come into contact with it. Notice the grip and placement of the goalie’s hands as he catches the ball. His hands are shifted more towards the sides, rather than placed more forwards towards the ball.

To make this scene believable with real physics, the goalie would need to recoil backwards as the ball contacts his hands while his own forces reacts with the ball and sends it flying in the opposite direction, although the goalie would not accelerate as fast as the ball does as his mass is greater. Another method is to have the goalie’s mass increase to withstand such a force from the soccer ball, that the reaction acceleration would be very small. The equation would work out as follows:

(small mass/incredibly fast acceleration) = (large mass/near fast reaction acceleration) where the goalie is applicable to Newton’s 3^rd law of motion as he is sent flying backwards and his reaction to the soccer ball sends it flying away from him, or

(small mass/incredibly fast acceleration) = (very large mass/very small reaction acceleration) where the goalie’s mass magically increases as he becomes a wall-like obstacle towards the ball.

This scene violates Newton’s 3^rd law so it can demonstrate the superior advantages the genetically enhanced team has over the Shaolin-trained soccer players. Although the final soccer match has a more serious tone, the play of equal and opposite action/reaction remains consistent and ties in nicely with the rest of the movie.

Director Stephen Chow artistically ties in the stylized action physics, which is exercised in many Chinese kung fu movies, and implements it for comedic use. Mainly used to exaggerate a scene or person, the deliberate play of Newton’s 3^rd law is a great way to make a character appear superhuman. By combining two vastly different disciplines, Shaolin kung fu and soccer, Chow combines the two in a manner that both are compliments to each other, rather than forcing kung fu into a soccer movie or a soccer movie with kung fu in it. Even though the play of momentum conservation is unbelievable in the real world, the consistent violation of the law makes it believable within Shaolin Soccer’s world.

-note to the teacher:

I changed the topic and outline of my essay since it was very unclear with its direction and objective. First, I mislabeled some of my examples under the blanket of Newton’s 3^rd law of motion. Second, it was difficult reworking the direction of the paper, so I just decided to rewrite the outline. I’m not sure if you want me to post the rewritten outline, but I can if you want it.