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.

The shape of the object, Whether the object is heavy or light, Whether the object traps air

An object does not float or sink only because it is heavy or light. The chapter shows that changing the shape of aluminium foil can make it float or sink, and that a tightly pressed ball may trap less air and sink while a looser one may float. Colour does not affect floating and sinking in these activities.

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.