Movies are a fun way to escape life and everything in it. Except that is not quite true. We cannot escape everything, otherwise movies become ridiculous rather than an escape. In Newton's third law of motion it is stated "for every action, there is an equal and opposite reaction"("The Physics Classroom"). This law is bent and even broken in numerous films for the sake of action and intensity. Some outlandish scenes in which this law is broken includes a bullet propelling a children's merry-go-round, a kung fu move with minimal force causing maximum damage, and a runaway bus crashing into a would-be hero.
In the film Shoot 'em Up, the protagonist places a baby on a merry-go-round in a park in hopes a good person will come and take care of it. As he walks away a woman approaching the baby is shot and killed by a sniper. The protagonist then realizes they shooter is after the baby. He then shoots the bars of the merry-go-round spinning it so the sniper can't get a clean shot at the baby. For this scenario to work, the speed and force of the bullet would need to be great enough that it could transfer to the merry-go-round in order for it to spin.
In doing research for this, I found that MythBusters did a segment on this very scene. They found that with a merry-go-round weighing around 500 lbs it would take 8.6 pounds of force to move it. Using a similar gun to the one in the movie they could not get it to move. They then kept moving up to higher and higher firepower. They discovered the higher powered shots pierced through the bars and did not transfer any of their energy. They attached steel plates to help stop the bullet and transfer the bullets energy to the merry-go-round. Even with the steel plate in place the merry-go-round would only turn at the most around 8 inches. They then re-engineered the ball-bearings on the merry-go-round to reduce the friction and found that with continuous fire of high powered ammunition they could keep the merry-go-round spinning ("MythBusters, 2011 season). In the law of action and reaction the force of the bullet from the gun shown in the movie is not strong enough in the real world to move the merry-go-round much less to spin it. The bullet being shot from the gun did not exert enough pounds of force upon impact in order to transfer the momentum to the merry-go-round.
Scene from the film Shoot 'em Up (https://www.youtube.com/watch?v=-xyQ1zmKId4)
Semi real world physics of a merry-go-round seen in a video game (https://www.youtube.com/watch?v=B0ODi_IL1jE)
In the film Kung Fu Panda, a move called the "Wuxi Finger Hold" is introduced as the most powerful move. It is performed by the attacker harnessing their Chi and holding an opponents finger with their index finger and thumb while the pinky is straight. To execute the move, the pinky is then flexed ("Wuxi Finger Hold"). This small action then causes a gigantic destructive reaction. In order to understand this, the closest thing I could find in real life to compare this to is Bruce Lee's one-inch punch. The one-inch punch is preformed by a closed fist approximately one inch from the chest of the target. With a concentrated Chi the fist is then struck to opponents chest. It is described as an explosive force produced from harnessing your Chi ("One-inch punch"). Both the Wuxi Finger Hold and the one-inch punch, from the outside look as if a very small action produces a major reaction. Despite initial observation, upon further investigation it can be seen that the one-inch punch actually utilizes the entire body. The person using the one-inch punch draws force all they way from their toes up through their legs, core, and arm out through the fist. The Wuxi Finger Hold on the other hand does not have such a draw of power. Instead the main proponent is the use of a Chi. Chi defined by Merriam-Webster is a "vital energy that is held to animate the body internally" or life energy ("Chi"). However, the Chi in both cases was not measured so it cannot be taken into account for a comparison. In no way can the action and transference of energy from flexing a pinky move to the index finger and thumb to create a reaction anywhere remotely similar to the one seen in Kung Fu Panda. Unless, of course, it was paired with a supplemental device, such as explosives.
Scene from Kung Fu Panda (https://www.youtube.com/watch?v=31P4DgkW9Ns)
Scene from television show Stan Lee's Superhumans, showing Shaolin monk Shi Yan Ming demonstrating a one-inch punch. (https://www.youtube.com/watch?v=wgVUMrjy2GA)
In the television show Smallville, a teenage Clark Kent (aka Superman) stops an out of control bus from crashing into a sleeping homeless person. He stops the bus by stepping in front of it and using his shoulder and body to stop the bus. The front of the bus crumples around his body as he absorbs the impact, not moving from his spot. Super energy absorption is not listed as one of Superman’s powers so that energy has to go somewhere. Either Clark would have to weigh exponentially more than the bus in order for him not to move or he would have to push down on the ground to dissipate the force of the bus. If he were to push down though the force into the ground, the asphalt would have cracked and he would have gone down partially into the ground. Trying to understand how something could stay in one spot but stop a bus I discovered something called a bollard, which acts as barrier, but looks like a pillar. They rise out of the ground to obstruct traffic from going a certain direction. Once they are raised, and even during raising, they can stop a vehicle in its tracks. They are built out of steel tubing and rise with the use of hydraulics. They work by dispelling the force of the impact to all of the ground surrounding the imbedded base ("Slimline Rising Bollard"). For Clark to stop the bus in the real world the force of the bus's impact needs to transfer somewhere, it cannot be absorbed into his person.
Image from television show Smallville depicting Clark Kent stopping a bus with his body
Video clip of bollards stopping moving vehicles. (https://www.youtube.com/watch?v=hCSsope5vOA)
Each of these scenarios demonstrates Hollywood's ability to manipulate the laws of physics in order to create a grand effect to catch the audiences’ attention. As demonstrated in these examples, bending the laws of physics must be done with care, and perhaps even other laws must be created to be put in their place to allow them to function. In Shoot ‘em Up, Kung Fu Panda, and Smallville, the creators rely on the audience to believe in the character’s ability to defy physics based on assumed skill beyond the obvious realms of physics.
Cites used:
"The Physics Classroom." . N.p.. Web. 21 Oct 2013. <http://www.physicsclassroom.com/class/momentum/u4l2a.cfm>.
"MythBusters (2011 season)." Wikipedia: The Free Encyclopedia. N.p.. Web. 21 Oct 2013.
<http://en.wikipedia.org/wiki/MythBusters_(2011_season)
"Wuxi Finger Hold." Kung Fu Panda Wiki. N.p.. Web. 21 Oct 2013. <http://kungfupanda.wikia.com/wiki/Wuxi_Finger_Hold>.
"One-inch punch." Wikipedia: The Free Encyclopedia. N.p.. Web. 21 Oct 2013. <http://en.wikipedia.org/wiki/One-inch_punch>.
"Chi." Merriam-Webster Dictionary.com. Encyclopedia Britannic Company. Web. 21 Oct 2013. <http://www.merriam-webster.com/dictionary/chi>.
"Slimline Rising Bollard." SafetyFlex. N.p.. Web. 21 Oct 2013. <http://www.safetyflexbarriers.com/products/anti-terrorist-security/slimline-rising-bollard/>.
