There is this show “Weapon Masters” – I think it comes on the discovery channel. It is not a bad show. The basic idea is that they have this history guy talk about the historical aspect of some type of weapon and this other guy tries to make an improved version. Last night the goal was to recreate the original flame thrower mounted on a boat.
They found a boat and they needed to test it’s sea worthiness. The builder guy (sorry, I don’t know his name) estimated that they would have 1000 lbs of equipment in the boat. To simulate this weight, they put 4 guys and two barrels of water in the boat and motored around.
After a little bit, the history guy noticed one of the barrels was leaking water. *”Quick! Put your finger in the hole before we all sink!”* he said. This is where he doesn’t understand floating. I think I can explain his error with two simple pictures:
The first picture has the boat with the water in the barrel. The second picture has some water that has leaked out. Either way, the total mass of water in the boat is the same. If you would like to talk more about floating, [here is my post about MythBuster’s lead ballon](http://blog.dotphys.net/2008/09/mythbusters-how-small-could-a-lead-balloon-be/) – same idea.
I think the weapon master history guy should have said:
*”Quick! Plug the hole before my shoes get wet! But, we won’t sink because the mass of water is the same no matter if it is in the barrel or in the boat.”*
2 thoughts on “‘Weapon Masters’ doesn’t understand floating”
Everybody knows water is heavier when it is flatter. That is why there is capillary rise, raindrops high in the sky are round, high altitude lakes are precipitously deep, and oceans – defining the geoid – are flat at their tops.
Make a solid ball of clay. Place it on a hard surface. Pound on it. The more you make it heavier the flatter it gets. A sufficienctly large gravitational field would also flatten it – by having it collapse flat under its own weight. See? Flatter is heavier. Pancakes are flat, loaf bread is chunky. Which weighs more? Chairs are light, tables are heavy. A door hinged upright moves with a fingertip. Try opening a flat door to a root cellar.
A mercury barometer has its narrow mercury thread spontaneously rise a full 76 centimeters straight up. You don’t see the barometer’s flat pool of mercury rising, do you? The only difference is the shape. Flatter is heavier.
Hah! I love Diversity’s comment! Hilarious!