Die Hard

“Hard to kill” was released in the late 1980’s considered by many a Christmas hit of all times. Others believe is an exciting and tense action movie. Moreover, for some it was a franchise which subsequent sequelae were very disappointing.

Besides general opinion, one have to admit that the first movie, premiered in 1988, was one of the most memorable movies of its time, it has transcended generations and shows what can be achieved with a simple premise, a great primary character and a lot of suspense. “Hard to Kill” is the movie that launched its protagonist, Bruce Willis, as a Hollywood hero. It ended up being historically influent and pertinent to the point that his future films contained some of that magic action displayed in different contexts. 

John McClane (Bruce Willis) is a New York cop who is traveling to LA to see his kids and wife Holly (Bonnie Bedelia), who moved to that city due to her work with Nakatomi Corp. When arriving to Nakatomi Plaza, he encounters Holly’s boss, Joe Takagi, and her work partner Harry Ellis. Holly and John went to a private bathroom where they had a fight. When Holly returns and prepares herself to give a speech, thirteen armed terrorists, led by Hans Gruber (Alan Rickman), take control of the building, and retained as hostage all of the 30th floor occupants, the only remainders in the building. Fortunately, they did not notice John and now he must figure out how to save the hostages before the terrorists get away with their plan. 

In one of the scenes, McClane tries to scape two of the abductors by hiding in an elevator gap and he does it by using his machine gun’s belt. The belt brakes and McClane falls to the depths of the building. After 13 meters of free fall, he manages to grab with the tip of his fingers the border of a platform and stays safe and sound. 

How realistic is this scene? To answer that question, we need to analyze it by a physics lens. Let us formulate the following questions: What velocity John McClane reaches at 13 meters of the fall? How big is the force that his finger receives when grabbing from the border of the platform?

First, we need to find out how much time does it takes him to travel those 13 meters. To calculate this, there is no need to know his weight since, as demonstrated by Galileo Galilei, all objects fall at a same velocity independently of its mass. Thus, by the free fall time formula, he would take 1.63 seconds, reaching a velocity of 57.5 km/h, that at the end would produce a force of 1,020,240 Newtons. All this calculation allows us to conclude that John McClane has enough force to carry an airplane by just using the tip of his fingers. ¡That is impossible!

Now, let me ask you a question. Do you think with this analysis it would be more interesting and attractive to teach physics concepts? Could Hollywood’s movies be the raw material from were math and physics classes arise?

More exercises

Would you like to have even more tasks for your own lessons? On more than 130 pages in “The Physics of Hollywood” you will find numerous additional tasks (and solutions) for your physics lessons. Available at Amazon (click).