Science HELP!?

Question

Explain why some objects floar while others sink. It has something to do with water displacement. Can you explain how much it has to displace to float, and whether it's the density or mass or volume of water that is displaced.

Answer 1

An object floats in water if its Density is less than the Density of water. Density is defined as mass(or weight) divided by volume. If an object has less mass then the same volume of water, it will float. If it has more mass than the same volume of water, it will sink. If equal, it will neither float nor sink.
If an object's density is low enough to float, it will float higher (and displace less water) if it has lower density.
Any object that is as dense or denser than water will displace its full volume of water.

Answer 2

While it isn't completely wrong to say that an object will float if its density is less than the liquid it is in, its not quite right either.
An object will float if it displaces (more than) its weight of the fluid. Thats why a steel battleship floats even tho steel is much denser than water. When people say density, they mean "average" density of the volume where the water is excluded, ie the objects weight divided by its displacement volume. Why? Because the liquid flows and gravity will pull it around and down under the boat because the boat is lighter. Since the density of water is (very slightly) greater as the depth increases and most things are not compressible, things with exactly the same weight as the volume they displace will float. But I wouldn't want to be out in a boat with the weight of the water of displacement exactly the weight of me and the boat. The smallest wave or even a bug landing on the boat would sink it. Objects with weights larger than their displacement volumes sink because gravity pulls them down and the water flows out of the way.

Answer 3

If something is more dense than the water it will sink, and vice versa. How much water displaced tells you the volume of the object that is dropped in the water.