The Bedtime Scientist

A question

Why do heavy ships float?

A calm, true answer. Then, if the wondering keeps going, the whole episode.

The short answer

Because of shape, not weight. Anything you put into water pushes some water aside, and the water presses back upward exactly as hard as the water that moved weighs. That upward push is called buoyancy.

A solid block of steel sinks. The same steel shaped into a hollow hull floats, because now the whole shape, air and all, shoves aside far more water than the ship weighs. The ship is not fighting the water. It is being held up by it.

Go deeper tonight

The Giant Ship That Floats

The full episode, in one calm voice, with nothing that startles.

The episode

The Giant Ship That Floats

0:00 10:59
Sleep timer

Read the guide for this one in the morning.

This connects to

Water Force and machines

One idea turns up in many different nights. Follow one and the library starts to join up.