# Hollywood and Physics

We’ve all seen these kinds of movies. After a fast and dramatic chase, the bad guy jumps out of the car, determined to end the good guy once and for all. His evil plans have been thwarted for the last time! In self-defense, the good guy is forced to take a shot and when the bullet hits, the evildoer is thrown violently backwards as a result of the impact and through the nearest shop window. Once the hero is reunited with the love of his life, the credits roll and we are left to wonder if that’s really how physics work.

In a previous example we calculated the momentum of a common 9 mm bullet (p = 5.4 kg m/s). Suppose the m = 75 kg evildoer gets hit by just this bullet. Since the bullet practically comes to a halt on impact, this momentum has to be transferred to the unlucky antihero for the conservation of momentum to hold true. Accordingly, this is the speed at which the bad guy is thrown back:

5.4 kg m/s = 75 kg ยท v’

v’ โ 0.07 m/s โ 0.26 km/h โ 0.16 mph

This is not even enough to topple a person, let alone make him fly dramatically through the air. From a kinematic point of view, the impact is not noticeable. The same is true for more massive and faster bullets as well as for a series of impacts. The only thing that can make a person fall instantly after getting shot is a sudden drop in blood pressure and the resulting loss of consciousness. But in this case, the evildoer would simply drop where he stands instead of being thrown backwards.

This is not the only example of Hollywood bending the laws of physics. You’ve probably heard the weak “fut” sound a Hollywood gun makes when equipped with a silencer. This way the hero can take out an entire army of bad guys without anyone noticing. But that’s not how pistol silencers work. At best, they can reduce the the sound level to about 120 dB, which is equivalent to what you hear standing near a pneumatic hammer or right in front of the speakers at a rock concert. So unless the hero is up against an army of hearing impaired seniors (which wouldn’t make him that much of a hero), his coming will be noticed.

This was an excerpt from my Kindle book: Physics! In Quantities and Examples

For more interesting physics, check out my Best of Physics selection.

# The Rise of the Sequels (1980 to 2012)

Did you also have the feeling that more and more of the top movies are sequels? If yes, then you were absolutely right. Starting with the turn of the millenium, Hollywood realized that sequels are cash cows and a wave of sequels flooded the market (with great success). I analyzed the number of sequels in the top 10 highest grossing films (numbers taken from Box Office Mojo, a fantastic data source for movie fans). Here’s the graph:

In the 80s there were on average about 2 sequels in the top ten each year. In the 90s this declined to only 1 sequel, there even were some years (1993, 1994, 1996 and 1998) without any sequels in the top ten. It seemed that Hollywood was turning away from making sequels. But in the 2000s the situation changed noticeably, on average 3 sequels made it into the top ten. In 2003 and 2007 half of the top ten consisted of sequels! And it seems that these peaks are becoming the standard for the 2010s. The year 2011 set a new record with 7 sequels among the top ten. And with so many high quality sequels coming up (see here: http://www.imdb.com/list/-kbo5fy-BCo), we might even see this record broken in the near future.