Why does a battleship float

If your boat meaningfully increases the water level, like it must in your example, you have to play some mental gymnastics with the definition of "displace" to arrive at the correct answer. That's not to say that Archimedes' Principle is wrong, just that the informal phrasing gets a bit tricky to apply. The formal version, involving moving water upwards against the pull of gravity, does not run into any such complications. For the interested, here is a little illustration I made once, to defend someone called 'Marilyn vos Savant'.

I didn't believe what people wrote in there against her statement, about a battleship floating in a bucket of water. I am very happy to see, that everybody in here knows what is right.

Here is the illustration:. As the battleship is placed in the giant tub, the water along the sides rises to a height, h. This pressure x the area of the bottom of the ship equals the weight of the ship, so it floats. Sign up to join this community. The best answers are voted up and rise to the top. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Learn more. Can a battleship float in a tiny amount of water?

Asked 2 years, 11 months ago. Active 2 years, 11 months ago. Viewed 7k times. Improve this question. SlowMagic SlowMagic 9 9 silver badges 12 12 bronze badges. This requires displacing Ax0. Buoyancy is opposing it. Fill the tub, then put it in; now either go find a mop or run around naked screaming.

Show 1 more comment. Active Oldest Votes. Improve this answer. Real ships have lots of air inside, so they weigh less than the same volume of water, so they float. Mike W. Here's a cool experiment you could try. Fill your sink with water, then put a bowl in it. Now see how much weight you can put in the bowl before it sinks. You could even pour in water as the weight. If you use water, look at how high the water comes up on the inside and on the outside of the bowl as you add more water.

Is it the same or different? And by the way, isn't it cool that it doesn't matter how deep or shallow the water is?

If something floats in 2 feet of water, it will float in feet of water! I hope this makes sense. The buoyant force depends on how much water an object displaces. The larger the object, the greater the buoyant force it experiences. Ah, but will that object float? So a large hollow object might float because large means more water displaced — so more buoyant force — and hollow means relatively little weight.

A small solid object might not float, however. Less water displaced results in a smaller buoyant force. But the weight of the water it displaces is more than the weight of the aircraft carrier, so it floats.

Me, I weigh more than the water I displace, so I sink. In technical terms, the density of a body is defined as the weight mass of the body in kilograms kg divided by its external volume in cubic metres m 3. From the above, only oil and wood naturally float in water. This is because fluids and materials that float in water have densities that are less than the density of water. In other words, an object's buoyancy is determined by its density in relation to the density of the surrounding liquid.

When applying this principle to ships, it is natural to question how a ship that has a hull made of steel, which has a density eight times greater than that of water, can float. A steel bar would sink, so why don't ships? Archimedes In the third century BC, the Greek mathematician and philosopher Archimedes discovered the principle of buoyancy while relaxing in a bathing pool.

When he entered the pool he noticed that water spilled over the sides and that he felt lighter. Archimedes realised that the amount of water that spilled was equal in volume to the space that his body occupied, and concluded that an object in a fluid experiences an upward force equal to the weight of the fluid displaced by the object. Because the upward force equals the weight of the fluid displaced, an object must displace a greater weight of fluid than its own weight in order to float.

That means that in order to float an object must have a lower density than the fluid.