Being home for holiday breaks usually involves lifetime movies on reruns in the background of cooking all day. Over this break, one of the movies playing in our family room was Titanic, the classic 1997 film. * Spoiler Alert *, the boat sinks and our main protagonists are left to fend for themselves in the 28 degree waters. Rose is able to climb onto a door from the sunken ship but Jack is left to freeze to death since there is not enough room on the door for the two of them. With all the emotional investment in the movie, you can’t not be upset because it seems clear that Jack and Rose could have fit on the door and escaped the wreckage together. However, director James Cameron in a recent interview with Vanity Fair explained that this scene is actually true to the physics of the situation. He says, “I was in the water with the piece of wood putting people on it for about two days getting it exactly buoyant enough so that it would support one person with full free-board.” Cameron spoke about how he was a stickler on the physics of it. If we look at the equation
v (displaced)/v (object) = p (object)/p (fluid)
the density of wood is around 7000 kg/m^3 and water is 1000 kg/m^3 so the percent submerged would be 70%, and this is without the addition of a full-grown adult. Therefore, there had to be enough changes to the door to allow for one person to be fully out of the water on the door so two people would have taken more altering that would be far from accurate. I looked into a Mythbusters episode in 2012 they actually had on this topic, and they found that the only way both Jack and Rose could have fit on the board would have been if there had been a lifejacket under the board to aid in the buoyancy. It appears the physics and the script are compatible, but regardless people still love to debate the fact.