EXPERIMENT Use the piece of aluminum foil to make a water-tight boat. See if you it will float. Now take the aluminum foil boat and crumple it up into a tight ball and put it back on the water. Does it float now? Why?

Why do boats float?

Did you ever notice that when something floats in water, part of it is actually under water?

This is a heavy boat…why is it floating instead of sinking? The boat will sink only so far into the water…why?

As the boat sinks (even a little bit) it pushes away the water until that amount of water weighs the same as the thing that is floating.

If the thing you try to float is too heavy, it cannot push away enough water to be the same as how much it weighs. If that happens, the thing will sink. Two equal mass concrete shapes

Any boat will sink if you put enough stuff inside it. As the boat is loaded, it sinks deeper, displacing more water, and so the buoyant force increases in order to match the weight of the boat and its cargo.

The amount of buoyancy an object has is determined by the density of the object.

Small, heavy things like a marble or a rock cannot float because they cannot push enough water out of the way to be the same as how much they weigh.. Buoyancy has to do with DENSITY

So remember, anything that floats weighs the same as the water it has pushed out of the way.