Home Alone Physics

Home Alone is an American Christmas comedy film, written in 1990; produced by John Hughes and directed by Chris Columbus. It is featured by Macaulay Culkin, Joe Pesci, Daniel Stern, John Heard and Catherine O’Hara. This movie is about an eight year old kid, called Kevin (Culkin), who has to defend his house from two burglars, Harry and Marv (Pecsi and Stern), after his family goes away for Christmas vacations and accidently leaves him behind.

The proposed scene shows thieve Marvin, crawling in to the house through the basement. In the center of the room, he pulls an antique electrical cable to turn on the lights. In step of turning on the lights, he is hit by an electrical iron that falls through the laundry conduit. In the movie, the iron falls at about 3.5 seconds.

How could you use this movie, mainly this scene, in a Physics class to teach concepts such as, acceleration, free fall, potential energy and kinetics?

We propose the following tasks:


  1. Watch carefully the movie excerption and measure the time the iron takes to land on Marvin’s head. Calculate the house height using the time given. Does this sounds realistic?
  2. From a previous scene it can be estimated that the house, from the basement to the attic, has about 13 meters of altitude. Calculate the time that it would take for the iron to fall from the top.
  3. What height would the house have on the moon or Jupiter, if the falling time in the movie is correct? ()
  4. Calculate the realistic falling time on the moon and Jupiter, using a specific house height (13 m).
  5. In which celestial body can be verified what happens in the film?

In this great book you may find answers and explanations to these and other questions concerning physics concepts. Films such as, Fast and the Furious, Spiderman and The X-men, are some of the many options offered here.


The physics in Mission Impossible: Ghost protocol

Mission Impossible has been loved by all ages since its release as a television series in 1996. A mixture of action, adventure, science and technology makes it attractive to the viewers. 

When arriving to the big screen, Mission Impossible served as a preamble for Tom Cruise’s stardom and consecrated him as an elite actor. The amazing body to body fights, which is the franchise presentation card, have evolved to be even more spectaculars. We must not forget the easiness of exploding things is this movie; perfect example of this we can find it in Mission Impossible: Ghost Protocol

In this film, Ethan Hunt has to save the world from an atomic war. During the movie, he goes up an exterior wall of Burj Khalifa, which has a high of 828 meters, using a special kind of gloves. After one the gloves malfunctions, Ethan remains hanging from the glass window for various seconds with only one hand. But, is this mission impossible? Is a glove’s surface big enough to sustain Ethan Hunt? Which is the least surface that the glove has to cover to sustain his weight?  

As you can see, this scene may result very attractive to explain and understand physical concepts such as pressure, the Pascal principal, Newton’s laws, etc. Examples like this one, explained in details, and many others can be found in the practical book, The physics of Hollywood.

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).



Duro de Matar

Para finales de la década de los 80’s, sale al estreno la película “Duro de Matar”, considerada por muchos como una de las mejores películas “navideñas” de todos los tiempos. Para otros, es una emocionante película de acción, e incluso, para algunos, se trata de una franquicia que fue forzosamente estirada en la que sus subsiguientes secuelas fueron cada una más decepcionantes que la otra.

Sin importar cuál sea la opinión general, hay que admitir que la primera película, la original de 1988, es una de las películas más memorables de la época, que ha trascendido generaciones, y que demuestra todo lo que se puede hacer con una premisa sencilla, un gran personaje principal, y mucha tensión y suspenso. “Duro de Matar” es la cinta que convirtió a su protagonista Bruce Willis en un héroe de Hollywood, y terminó siendo tan influyente e históricamente importante, que sus futuras filmaciones buscan recrear esa magia de acción original desde diferentes contextos y puntos de vista.

John McClane (Bruce Willis) es un policía de la ciudad de Nueva York que se dirige a Los Ángeles para ver a sus hijos y a su esposa Holly (Bonnie Bedelia), que se mudó a Los Ángeles debido a un trabajo en la Corporación Nakatomi. Cuando llega a Nakatomi Plaza, se encuentra con el jefe de Holly, Joe Takagi, y su compañero de trabajo Harry Ellis. Él y Holly van a un baño privado y se pelean. Cuando Holly regresa y se dirige para dar un discurso, trece terroristas armados liderados por Hans Gruber(Alan Rickman) toman el control del edificio y toman como rehenes a los ocupantes del piso 30, que son los únicos que quedan en el edificio. Afortunadamente, no se dan cuenta de John y él tiene que descubrir cómo salvar a los rehenes antes de que los terroristas se salgan con la suya.

En una de las escenas más intensas, McClane intenta escapar de dos de los secuestradores escondiéndose en el hueco del ascensor. Lo hace bajándose con la ayuda de la correa de su ametralladora. La correa se rompe y McClane cae a las profundidades. Después de unos 13 metros de caída libre, logra afianzarse con sus dedos del borde de una repisa y termina sano y salvo.

¿Qué tan realista es la escena? Para contestar esta pregunta, debemos analizarla desde el lente de la física.
Planteemos las siguientes preguntas guías. ¿Qué velocidad alcanza John McClane a los 13 metros de haber caído? ¿Qué tan grande es la fuerza que reciben sus dedos al aguantarse del borde de esa pared?
Primero, necesitamos saber cuánto tiempo le toma recorrer esos 13 metros. Para saberlo no necesitamos conocer su peso puesto que, según como lo demostró Galileo Galilei, todos los objetos caen a la misma velocidad independientemente de su masa. Así, mediante la fórmula para el tiempo en caída libre, tardaría en caer 1.63 segundos, alcanzado una velocidad de 57.5 km/h, que a al final produciría una fuerza de 1,020,240 Newtons. Todo esto nos permite llegar a la conclusión que John McClane cuenta con la suficiente fuerza como para lograr cargar un avión de pasajeros con tan solo usar la punta de sus dedos. ¡Esto es imposible!
Ahora te hago la siguiente pregunta. ¿Crees que con este análisis resulte mas atractivo e interesante enseñar conceptos de física? ¿Podrían ser las películas de Hollywood la materia prima que desarrollen las clases de ciencias físicas y matemáticas?

Ejemplos como este y muchos más encontrarás en el libro “La Física de Hollywood”. Este libro ofrece respuestas a preguntas acerca de física, donde maestros, estudiantes y amantes de la ciencia podrían disfrutar.


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).