Physics in Film

This is another movie we probably won’t officially review this semester, but I wanted the library to have a copy on hand. For car enthusiasts, it’s probably a must-see. For a physics class, you might think there’s not much to work with here. To some extent that’s true, but the movie does have one great physics scene: a 120 or so foot jump of a 1967 Shelby Mustang GT over the top of a traffic accident on the Vincent Thomas bridge in Los Angeles (view a clip of this scene on the Nicholls State U. website here). In the context of a “Physics in Film” class this scene is remarkable for one particular reason: it serves as the perfect contrast to the infamous bus jump scene in the movie “Speed” (view clip here). In “Gone in 60 seconds” the jump is depicted in a physically plausible (if highly dangerous) way; the car takes off with an appropriate launch speed and angle to make the jump and follows a realistic trajectory (we’ll analyze this scene in class), whereas the jump in “Speed” is not at all possible as portrayed in the movie. “Why does it matter?” you may ask. Maybe it doesn’t, but I would counter with the question, “If you can do the scene realistically and still make it exciting, why wouldn’t you?” For me, the scene in “Gone in 60 seconds” left me feeling “Wow!” The danger of the jump fits in with the plot – Randall Raines (Nicolas Cage) has already demonstrated he’s willing to give up everything (even his own life) to save his brother. If it’s going to take a nearly impossible jump over a log-jam of cars and emergency vehicles, so be it! The scene in “Speed,” on the other hand, left me feeling, “Oh, come on.” The plot is ludicrous as it is (a psycho ex-cop decides to hold a city hostage by booby-trapping a transit bus?), but the bus jump scene pushes the movie completely outside the realm of possibility. That’s not what I’m looking for in my action movies. So, my question to you is, why do Hollywood directors choose to film impossible scenes rather than construct equally exciting ones that are at least physically plausible? I think “Gone in 60 seconds” demonstrates emphatically that physically realistic scenes can still be exciting.

Another scene in this movie worth considering from the perspective of “Physics in Film” is the one where the police SUV gets knocked through the wall by the wrecking ball. It’s probably not realistic to think that the SUV would actually go through the wall (or that the cop involved wouldn’t have been more seriously hurt). Clearly that was a special “Hollywood” wall. Still, the scene was presented somewhat tongue-in-cheek. I mean consider the dialog following the scene:

G.R.A.B. special agent: “Are you alright?”
Patrol cop: “I think so.”
G.R.A.B. special agent: “Are you sure? ‘Cause you just went through a wall.”

Personally, I’m willing to forgive some lapses in physical reality, especially when they’re presented in a way that’s clearly not meant to be taken seriously, as in this scene.

This movie gets my vote for the worst movie physics of any of our feature films this semester; it even got ISMP’s vote as the #1 worst physics movie they’ve ever reviewed. To me, the bad physics is made even worse by the fact the movie takes itself way too seriously; there is very little humor; and I just don’t find myself connecting emotionally with any of the characters. So…

Assignment: The physics in this movie is so bad, your assignment is to try to keep track of all the physics blunders in the movie. You don’t have to work out all the details of why the physics is wrong, just give a brief description of each bit of bad physics you find in the movie. If you think you’ll need help, start by reading the ISMP review.

Please post your response on your blog by Monday, 29 Sep.

Ch. 14 – ISMP

OK, there are plenty of things to criticize in this movie from a physics perspective, but at least they get off on the right foot. The opening sequence describes pretty well the event most scientists believe killed off the dinosaurs (they even have the asteroid hitting the Earth in the correct location). It’s also true that something like this will happen again someday. After that, things get pretty sketchy to put it mildly. Of course, there is the obligatory destruction of NY City, even though the likelihood of a few stray meteorites hitting one of the largest cities on Earth are remote to say the least (remember 70% of the Earth’s surface is covered with water, so most likely the meteoroids are going to hit an ocean). Still, I find this movie entertaining. To me it never appears to take itself too seriously and there are some very humorous scenes. I’ll admit to even getting caught up in the stories of heroism and personal sacrifice. But when it comes right down to it, NASA’s plan to save the world (as portrayed in the movie) is pure bunk; it just wouldn’t work as we’ll discover in class.

Assignment: Come up with a plan of your own to save the Earth; hopefully one that will work. Remember, this scenario (asteroid collision threatening all humanity) will happen sooner or later, so it would be good to have a working plan. You can adjust any of the following variables you like: how much time you have, how big the meteoroid is, what it is made of, how massive it is, how dense it is. You cannot, however, adjust the fact that on final approach to Earth any meteoroid will be traveling at roughly 25,000 mph (1.1×10⁴ m/s – the escape velocity at the surface of the Earth). So, tell me, how are you going to save mankind? If you’re stuck, I encourage you to brainstorm with other members of the class.

Please post your response to your blog by Monday, 22 Sep.

Ch. 2 – Don’t Try this at Home
Ch. 5 – ISMP

pp. 57-82 – Don’t Try this at Home
Ch. 7 – ISMP

You could substitute just about any action movie here. Anything starring Arnold Schwarzenegger, Sylvester Stallone, Bruce Willis, Vin Diesel, etc. should do fine. They all have the same cliches and the same bad examples of physics. The two most widely violated physical principles in movies such as “Eraser” are the Law of Conservation of Momentum and the Law of Conservation of Energy. Mind you these are two of the most immutable laws of the universe for us mere mortals, yet somehow they don’t seem to apply in Hollywood action films. (You could add the Law of Conservation of Bullets to this list, too.) One of the most egregious examples of the violiation of the Law of Conservation of Momentum comes across this way: the hero can fire away on his/her gun with practically no recoil whatsoever, yet any bad guy hit by a bullet from said gun will be violently launched off their feet and into whatever structure happens to be behind them (often a glass wall or window). It just can’t happen that way!

Assignment: Analyze in detail any of the scenes where someone fires the rail gun and hits a victim, sending them flying. Your analysis should be centered around the application of the law of conservation of momentum. This will require calculating the momentum of each of the objects involved (shooter, victim, bullet, and gun) and then appropriately applying the law of conservation of momentum. Keep in mind that you may need to invoke conservation of momentum more than once. Also remember that objects can exchange momentum with other objects, provided the total momentum remains constant. If you have trouble, help each other out or write back to me for more input. As always, you should also feel free to comment on any other violations of the laws of physics that you happen to notice.

Please post your answers to your blog by Monday, 15 Sep.

pp. 49-56 – Don’t Try this at Home
Ch. 12 – ISMP