How Things Work

Leaf

A leaf will float in water because it is light and has air trapped in it. Iron nails, stones, and coins are heavy and will sink.

It floats

An empty steel bowl floats because it traps air inside, making it lighter than the water it displaces. Even though steel is heavy, the air makes it float.

Weight of the object, Shape of the object

Both weight and shape affect whether an object floats or sinks. Light objects tend to float, and changing shape (like with aluminum foil) can make the same object float or sink. Color and container size don't affect floating or sinking.

It sinks

When aluminum foil is pressed tightly into a ball, it sinks because it becomes denser and traps less air. The same foil floats when spread out or made into a cup shape.