Science Common Sense

215 - What causes an object to float or sink?

Imagine you have a toy boat and a rock. You throw the rock into a pool, and it sinks to the bottom. But the toy boat floats on top.

The reason this happens is because of something called 'density.' Density is how tightly packed the tiny particles, or atoms and molecules, are inside an object.

When an object is less dense than water (like the toy boat), it will float. If an object is more dense than water (like the rock), it will sink. This is because the particles in the rock are more tightly packed than the particles in water, making it heavier.