### Sorry Girls, "Titanic" Doors Were Made of Oak.

 Just let him up there, darn it! Photo courtesy of www.dailynewsdig.com
Unless you have been living under a rock, you have probably seen "Titanic" either when it first came out or in its 3D rerelease.  Spoiler alert.... the ship sinks and lots of people die, one of whom is the extremely attractive Jack.  He dies to save the love of his life, Rose, by placing her on a "raft" made out of what looks like a door as he stays in the freezing water dying slowly of hypothermia.  Through the tears, more than one audience member was wondering why his grand hotness couldn't have fit on the raft too.  It looked like there was plenty of space up there if Rose could have just scooted over a bit. In fact, there is a meme going around about just this.  In a recent interview, director James Cameron answered the question many of us have been asking for the past 15 years.  It wasn't the space on the door, it was the door's buoyancy. So was this true or not? Does physics support the idea that Jack didn't have a chance? Heck, would Rose have been able to survive? Physics can tell us the answer to this age old romance question.

Buoyancy is the force that makes something float.  It depends on the volume of the floating object and the density of the liquid in which it is floating.  For something to remain above the water level, the bouncy force must be greater than the force of gravity pulling down on the object.

In the case of Rose, Jack and the door, the buoyancy force of the ice cold salt water pushing up on them must be greater than the force of their combined weight.  The force pushing up depends on the volume of the object submerged and the density of the water in which it is floating.  So lets see how that stacks up.  Looking at the raft in stills from the movie and looking up Kate Winslet's height, we can estimate that the raft is about 6'x3'x5" and the density of ice cold salt water is 1000kg/m^3.  Our heros would survive only if the top of the raft were at least at the water level.  So let's assume the volume submerged is that of the full door, 0.254 m^3 (keeping it all in metric).  Multiply this by the density of salt water and the pull of gravity and you find that the buoyant force is 2490N.

If the weight of Jack+Rose+door is greater than 2490N, they are all in hot water (or, I guess freezing cold water).  Seeing as there was much controversy of Kate Winslet's weight, it was easy to find out that at the time of the movie she weighed 125lbs, or 549N.  It was a little harder to track down Leo's weight, but he topped out at a whopping 161lbs or 715N.

Finding the weight of the door is a bit trickier.  Weight is volume times density times the pull of gravity, but its not clear what the door is made of.  There were three types of wood commonly used on the Titanic, teak, oak and pine with densities of 980kg/m^3, 770 kg/m^3 and 420 kg/m^3 respectively.  If the door were teak, the weight would be 2,440N, oak would be 1,147N and pine tops out at 617N.

Teak would barely float on its own so Rose and Jack would be headed into an eternity of sappy music together.  If the door were pine, the total force of Jack+Rose+Door would be 2,313N and all would have been well in the world of middle school girls across the globe.  But darn you Mr. Cameron, pine was simply not good enough for your movie!  The door was most likely oak which has a weight of 1,920N so adding the adorable couple would give a weight of  3,185N, just a little too heavy.  Subtract Jack and you get a force of 2,470N, just light enough to float and allow Rose to go on and live a long and happy life as Jack's frozen body spent continued to bob in the ocean.  Before he died in his melodramatic, tear-jerking manner, he made her make him a promise.

"You must do me this honor.  Promise me you'll survive.  That you won't give up, no matter what happens, no matter how hopeless.  Promise me now, Rose, and never let go of that promise."

She wouldn't have had to make that promise if James Cameron had just used pine!

*Mathlete would like to note that she feels the movie would have been improved with teak doors and only rewatched the ending grudgingly in the name of science.

1. Never mind the door. Jack had been up to his neck in freezing water chained to a pipe for maybe a half hour before Rose finally freed him. She herself had to wade around below decks looking for him. They both would have been dead of hypothermia long before the ship sank.

2. I haven't seen the movie. I win.

1. You did read the blog post, so technically, I win.

2. The only thing more awesome than the post plus this comment would have been the ending where they plugged the leaks with Jack, Rose, the mom, and the fiancee. (Possibly also the three dogs who survived IRL, your mileage may vary.)

3. I thought I was living over a bakery, but apparently I live under a rock.

4. Titanic are designed with best qualities.vist onTitanic Events in Belfast

5. Hey thanks for the link to our site mentioning the Meme ;-)

1. No problem! It cracked me up and I couldn't help figuring out the math behind the whole thing.

6. Except Jack had part of his body on the door, so even though his full weight wasn't on it, he would certainly add the extra 20 N needed to pull down an oak door. Since the door floated with Rose and part of Jack on it, it must have been pine, meaning Jack should have just come all the way up.

1. Wow, excellent point! I hadn't even thought of that.

2. It could have been slowly sinking as he held on, which we can't exactly tell, but just givin' theories.

3. i havent seen the movie for a while but if hes treading water would that not help stop them sinking

4. I was thinking the same thing. His body would automatically try to stay moving to generate heat so he probably wasn't putting all his dead weight on it.

5. But eventually he was putting dead weight on it when he died

7. Also, the movie just wouldn't have been as good if Jack had lived. Yes, movie goers might have left a little happier, but the ending would have been too cliche, "Everybody lives, YAYYYY." Also, 1500 casualties is a very large number and hard to wrap your mind around. Falling in love with one of the main characters for the past three hours just to watch him freeze to death allows you to almost feel the grief that many people felt when the Titanic actually sank.

8. Also, the movie just wouldn't have been as good if Jack had lived. Yes, movie goers might have left a little happier, but the ending would have been too cliche, "Everybody lives, YAYYYY." Also, 1500 casualties is a very large number and hard to wrap your mind around. Falling in love with one of the main characters for the past three hours just to watch him freeze to death allows you to almost feel the grief that many people felt when the Titanic actually sank.

9. Hey people do u know how many doors were on that ship just think if people knew the boat was going down and its cold water wouldn't you be on board thinking if you don't get a boat what am I going to float on everyone could have used to door and saved a lot of lives smh

10. Hey people do u know how many doors were on that ship just think if people knew the boat was going down and its cold water wouldn't you be on board thinking if you don't get a boat what am I going to float on everyone could have used to door and saved a lot of lives smh

1. Chief Baker Charles Joughin decided to have a small drink of spirits before he headed up to the boat deck to help load his designated lifeboat. After that job was finished, on his own cognition, he threw fifty deckchairs overboard before going back back to his own cabin and having another drink.

The Chief Bakers journey on the Titanic ended with him clutching the outside of the poop deck rail on the starboard side as the ship slid into the sea. He then spent at least two hours bobbing about in the cold ocean before he was picked up.

It would seem that the optimal condition to be in for surviving the Titanic was drunk!

11. If I'd had a door which I could keep for myself, I would've waited until the prow of the ship was partially submerged so that I could ease myself into the water. Even with a floating door, staying as dry as possible would've been critical.

12. they could have exchanged positions time to time to avoid hypothermia

13. What about air pockets? That door seemed to have awfully large, deep panels.

14. HoW did the door come off its hinges in the first place? They did not really have the time to scrounge around for a screwdriver to remove it from its doorframe. And why did only one door "break away" from its frame?

1. Judging from the picture it probably wasn't removed from the hinges. All those people forcing themselves through the opening probably broke it off.

15. Where does the assumption that the door was 5' thick come from? Sounds rather excessive to me.

16. Since this movie, when other comedians say "I can put you on the door at my show" we are more reluctant to accept the offer.

17. This is right after Rose says 'Jack, I'll never let go . . .' and then she does. I guess she meant it metaphorically.

18. It's simple: You can't have the "romance with the bad boy" fantasy if the follow-up is "living day-to-day with the bad boy" because everyone knows he would have been a lousy boyfriend. Jack dying gave Rose so much more-- She could have the fling she wanted without the messy commitment. She could live her life dreaming of her fantasy with Jack without ever needing to pick up his skidmarked drawers from the bedroom floor or argue with him about bills. He remained however she wanted to picture him, immortalized as a romantic lead in her mind.

19. It wasn't a door.

1. Thanks, Jerry.

2. it was another titanic

### How 4,000 Physicists Gave a Vegas Casino its Worst Week Ever

What happens when several thousand distinguished physicists, researchers, and students descend on the nation’s gambling capital for a conference? The answer is "a bad week for the casino"—but you'd never guess why.

### Ask a Physicist: Phone Flash Sharpie Shock!

Lexie and Xavier, from Orlando, FL want to know: "What's going on in this video ? Our science teacher claims that the pain comes from a small electrical shock, but we believe that this is due to the absorption of light. Please help us resolve this dispute!"

### The Science of Ice Cream: Part One

Even though it's been a warm couple of months already, it's officially summer. A delicious, science-filled way to beat the heat? Making homemade ice cream. (We've since updated this article to include the science behind vegan ice cream. To learn more about ice cream science, check out The Science of Ice Cream, Redux ) Image Credit: St0rmz via Flickr Over at Physics@Home there's an easy recipe for homemade ice cream. But what kind of milk should you use to make ice cream? And do you really need to chill the ice cream base before making it? Why do ice cream recipes always call for salt on ice?