Why do stones sink?

Question

Why does a small stone weighing a couple of grams sink in the ocean when massive ships weighing tons can float?

Answer 1

Density.

When something is denser than the substance around it, that something will sink. The opposite is also true where if something is less dense than the substance around it, that something will float.

The battleship floats, despite weighing thousands of tonnes, because its overall density is lower than that of water. Think of it this way, the battleship weighs less than water of the same volume.

It is the same reason why hot air balloon rises (hot air is less dense than atmospheric air), icebergs float (the crystals formed when water freezes make ice less dense than water) and oil floats on water (oil is less dense than water).

The same principle can be used to determine the weight of the ship/stone/whatever. The weight of something that floats or sinks in water is the same as the weight of the water that it pushes out as it floats or sinks. Put a 1kg brick into a full tub of water. Collect the water that spills out of the tub when the brick is put into the water and you'll find that the weight of the water collected is 1kg.

Similarly if you manage to put a 1000 tonne ship into a full (and big) tub of water, The weight of the water that spills out as the ship is being put into the water is 1000 tonnes.

Answer 2

The physics principle here is one of displacement. Object A will float in fluid B if the amount of fluid B that object A displaces (pushes out of the way) weighs more than the part of object A doing the displacing.
In more concrete terms, that tiny little rock of maybe a cubic centimeter in volume weighs more than an amount of water of the same volume.
Large ocean-going ships are designed such that they displace a very very large amount of water. Water may not feel very heavy when you only have a glass of it, but try picking up a couple of gallons of water, and you'll understand that water is actually pretty heavy. Those big ships displace enough water that the amount of displaced water weighs more than the ship.
A large part of this is that the ships are hollow. Air doesn't weigh very much, so if you took an oil tanker and crumpled it up so that there wasn't any air or oil or anything else left inside, the tanker would sink (pretty quickly at that).
You can even try a little experiment of your own to understand this better. Take a square piece of aluminum foil, and fold the sides up (about an inch on every side should do fine) so that you ave a makeshift boat. If you place it in a sink full of water, it will float easily. You can even add some pennies to it, and it will continue to float until the foil and the pennies together weigh more than the water they're pushing out of the way.
Now take that same piece of foil (or an equivalently sized one) and fold the sides up further so the bottom of your "boat" is significantly smaller. Start adding pennies again, and you will notice that it takes fewer pennies to sink the boat when the boat is more compact.

Answer 3

The answer is in the density of the material, I think. A stone's atoms are packed more densley than water. As a stone's atoms weigh more than the atoms of water, with the density, the stone sinks. Now, a ship has only part of that equation; the actual weight of each atom of a ship may weigh more than water's atoms. But density is the key, here, I think. Think "bubble". A ship is shaped as a bowl, not all packed in like a stone. Without the bowl shape taking advantage of the surface tension of the water and the air inside (after all, if the ship were stuffed to the gills with water, it'd be sunk already, right?), then the ship would be just like the stone.

Answer 4

Stones has a higer density (mass of the object /volume of the object) than that of the water's. The mass of the stone or any object doesn't determine if it would float of sink, only density would. Massive ships weighing tons, therefore it has a larger volume and mass, giving a lower density. The materials of the ships are the crucial elements of why the ships float. The iron of the ship would obviously cause the ship to sink due to its higher density than water, but the air sacs in the ship contain air--has a lower density. With air, the total and overall density of the ship would be lower than water's, that's why it would float.

Answer 5

Things float as long as the water they displace weighs as much as they do.
So, a ship, which is heavy but filled with empty rooms/cabins/holds etc. will float.
Put something into the holds and it floats lower in
the water it has to displace more water to equal the weight of the stuff put in the hold a stone no matter how small cannot go enough.

Answer 6

It's not to do with the weight of the stone / ship in itself but whether the overall density (the weight (or mass) divided by the volume) of the stone or ship is greater than that of the water. Remember that the big ships have an awful lot of air in them below the water line which reduces the overall density considerably. A stone, though, is solid stone all the way through (though sometimes volcanic rocks can float because they have lots of air bubbles in them).

Hope this helps

Answer 7

Don't listen to them talking about a stone being heavier than the water it displaces so it sinks.

Ignore nonsense about boats only having a metal shell, and the rest of the contents being mostly air, so that the ship sinks down in the water until it displaces an equal weight of water.

Mermaids can see a ship and hold it up because they have people inside.

They don't care about stones.

That's the truth.

Answer 8

A stone is heavy so it sinks. A ship is hallow inside and this keeps it from sinking. If there is a leak in the ship and it fills all the compartments then the ship will sink. If that makes any sense.

Answer 9

Because of density. Though the ship is heavier than the boat, the boat's weight is spread evenly and over a large enough area, so it will not sink. The rock on the other hand is smaller and the matter is compressed into a smaller area or volume, so it sinks. Its "density" is higher than the boat's.

Answer 10

Due to buoyancy. The shape of the ship's hull makes it float. A small rock has a density more than water that makes it sink.