jueves, 4 de mayo de 2017

Physics and movies: Titanic

[Spoiler alert: the ship sinks]

In one of my last lessons, a controversy regarding the movie Titanic came up. Just after the sinking of the ship, the two main characters, Jack (Leo Dicaprio) and Rose (Kate Winslet), try to keep themselves alive by laying on a wooden door. After a few attempts, they reach the conclusion that it was impossible because of the fact that the door didn’t have enough buoyancy to hold the two of them. As a consequence, only one them could survive, so Jack decides to let Rose lay on the door while he remains in the water. Finally, he dies due to the low temperature of the seawater and sinks. My female pupils, who consider this scene is one of the most romantic ones ever shot, tell me off when I express my doubts about the buoyancy of the door. Possibly Jack could have survived if Rose had let him up.


I have surfed the net and found some information.
  • According to this frame of the movie and others we can estimate that the dimensions of the door are 2 m · 1 m · 15 cm.
  • Jack (Leo Dicaprio) has a mass of 77 kg
  • Rose (Kate Winslet) has a mass of 63 kg
  • Some kinds of wood were used to build this famous ship. Each of them has a different density:
    • Teak: 980 kg·m-3
    • Oak: 770 kg·m-3
    • Pine: 440 kg·m-3
  • The density of sea water at that low temperature (we can assume it was very close to 0 ºC or even lower) is 1.028 g/cm3.

Exercise:
  • Do the math and calculate the maximum buoyancy force exerted on the door.
  • Figure out the total weight of the system door+Jack+Rose for each of the three types of wood mentioned before.
  • Compare that two forces.
  • What do you think? Did Jack have a chance? Did he die because he romantically decided to sacrifice his life to save Rose’s or just because she was mean?

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