The normal force

A book lying still on a table has its weight pulling it down, yet it doesn't fall, so something must push it up just as hard. That push comes from the surface: the table is squeezed very slightly and pushes back on the book, at right angles to its own surface. It is called the normal force, the support force of a surface. On a level surface with nothing else pushing, it is the same size as the weight, so a heavier thing gets a bigger normal force; if you also press down on the book, the table pushes back harder still. The normal force is also what makes friction grow when things are pressed together.

Depth 1 · Foundation

You know a surface pushes on whatever rests on it at right angles to itself (the normal force), that on a level surface it balances the weight of a thing at rest, and that it grows when the thing is heavier or pressed down harder.

Depths of understanding

1
Foundation
You know a surface pushes on whatever rests on it at right angles to itself (the normal force), that on a level surface it balances the weight of a thing at rest, and that it grows when the thing is heavier or pressed down harder.
Opens after
Balanced forcesA thing at rest has balanced forces on it, so something must balance its weight.Gravity, depth 2The normal force balances a thing's weight, so you need to know what weight is.

Your path here

What's still between you and The normal force, depth 1, in the order you can learn it.

Where it fits

Builds on

Balanced forces GravityDepth 2

This concept

The normal forceMechanics

Builds onThis conceptBalanced forces GravityDepth 2 The normal forceMechanics

Makes these deeper

Once you know The normal force, come back to these — they'll mean more.

Slippery and roughDepth 3The harder the surfaces press together, the bigger the normal force and the bigger the friction.