Physics in The Movie Hancock

            Countless superhero movies show us heroes with unparalleled, superhuman strength.  One example of this is in the movie Hancock.  Hancock is a superhero who can fly and has incredible super strength.  

One scene in the movie shows Hancock stopping a speeding train by just standing in its way.  From this example, we can calculate the amount of force it took for Hancock to stop the train.  For the sake of calculating an actual force, we will assume that the train had a mass of 489880 kg (average passenger train), and that the train was moving at a speed of 40 m/s (top speed for inter-city passenger trains) in order to calculate the train’s momentum. 

p = mv

p = (489880 kg) (40 m/s)

p = 19595200 kgm/s

As you can see a speeding train has an extremely large amount of momentum.  Now in order to calculate the force Hancock applied on the train, we must related the change of momentum to time.  In the movie, Hancock stops the train pretty much instantly, so for the case of calculations, we will assume that he stopped the train in 0.5 s.  As for the change of momentum, the final momentum of the train and Hancock will be 0 because both he and the train are completely stopped.  Hancock’s initial momentum is also 0 because he is standing still when the train hits him.

F = p_f - p_i / t

F = (0 -19595200 kgm/s) / 0.5 s

F = 39200000 N

That is a lot of force needed to stop that train.  To keep this in perspective, the Saturn V rocket used 35000000 N of force in order to lift off.  Here is the scene that is described:

https://www.youtube.com/watch?v=SD1vsiTjTfc