Inertia in Films
Movies often have to veer away from the realm of physical possibility in order to successfully create the desired scenes. There are many instances within films that portray actions and events that would never be possible in reality, but are quite suitable and acceptable within the film's unique world. This is mostly true of action thrillers and science fiction and fantasy movies. As an audience, we don't really care about these discrepancies, as the crazy fantastical effects are often used to enhance the tension of effect of whatever scene they are used in. And so without any hesitation, the normally hard unchanging laws of physics are broken time and again, and we couldn't care less. One of the very common laws of physics we break in our films is the law of inertia, Isaac Newton's first law of motion, which states that an object will preserve its velocity unless acted upon by an external force. The sheer amount of incredible scenes in films involving extreme motion or impact means that this law is one that is commonly thrown out the window. Any action scene, including fight scenes or vehicle chase scenes in a modern movie will probably break the law of inertia at least once in its duration. Films such as Gravity, the Star Wars Trilogy, and the Matrix Trilogy all have examples of this law being broken during their intense scenes.
Within Alphonso Cuaron's space thriller, Gravity, there are many minor and major physical inaccuracies in the way objects in space behave – from the gravitational stiffness of Bullock's hair to the behavior of the space debris as it orbited around Earth. In terms of inertia, however, there is one specific glaring fluke that is more obvious than the others. It occurs in the moment when astronaut Kowalski (played by George Clooney), attached to Bullock's character Ryan Stone, unhitches himself from the tether connecting the two of them together after her leg gets caught on the rigging in order to save her from getting detached and floating off into space. Even though the two of them stopped completely, the movie treated this scenario as if there was a constant force pulling Kowalski back into space as he hung on. In reality however, the fact that the two of them stopped moving outward completely should have meant that they were at rest relative to the space satellite, and thus there would have been no need at all for Kowalski to sacrifice himself by detaching from Stone. All that would have been needed to get him moving back towards the station would be a pull towards her from Stone, as there would have been no force resisting such an action.
The law of inertia is broken several times in the Star Wars trilogy each time a ship warps to light speed. But unlike in Gravity, the issue is that the consequences of inertia are unaccounted for in addition to there being the application of strange nonsensical forces. For one, the ships, after charging up their hyperdrives, reach light speed instantaneously, with little to no acceleration needed to get them to that point. The amount of force needed to accelerate the ship that quickly is completely unrealistic, and what's more the ships seemingly stop travel ling in a state of light-speed instantaneously as well, with nothing seeming to decelerate them to that point. If it were handled realistically, the ship would take quite some time to reach light speed (assuming it could), and a ton of time slowing down as well. In addition the people on board, along with many of the ship's components, would probably splatter upon the ship's walls, as due to inertia they wouldn't be able to accelerate to light-speed at the exact moment the ship does. They would remain at rest longer than the ship, which would burst forward, essentially slamming into them. Perhaps there are some unnamed, odd science fiction technologies that we are to assume allow them to survive and feasibly pull off such a jump, but as far as physical plausibility goes, it doesn't add up.
The Matrix films are full of intense, fantastical fight scenes in which the characters bend the realm of possibility through the manipulation of the matrix, the code that runs the reality of our world. The movements and abilities of the fighters were designed with this in mind, and the resulting sequences are extremely unreal and unique. This of course involves breaking the rules of physics, and there are several instances in which the law of inertia is messed with and broken. A big example of this is when one of the characters kicks or punches another with enough force that they fly far back into a wall or onto the floor several meters away. When this happens, the victim almost always moves through the air with his body relatively flat and unbent. In reality, a blow strong enough to send someone flying like that would cause the rest of the body to bend over the point of impact, as inertia would cause it to accelerate backward after the point of impact (assuming he wasn't crushed from the force of such a blow beforehand). The other obvious issue with the physics is the tendency for the fighters to maintain their inertia during these moments when they are knocked back in the air, or simply when they are jumping to their opponent much longer than they should, without the force of gravity affecting their velocity. This results in the characters floating or doing incredible stunts that would normally not be possible.
In all of these examples, the laws of inertia are tweaked broken in order to give their respective scenes more impact. Whether it's simply to enhance the fantastical nature of certain elements such as the light-speed technology in Star Wars, to make fight scenes appear more awesome and impactful like in the Matrix, or to serve as a plot point or an intense moment like in Gravity, the breaking of these physical rules is done in order to make each movie unique in its own way and to capture the imagination of the audience. Realistically, objects would follow the rules we are used to, and retain their velocities when appropriate and be accurately affected by external forces. But in these films, the extreme, odd portrayals of motion only serve as another method of fascinating the audience.