Pressure is a measure of force per unit area.

There is a cool thought experiment that you can do to help you understand pressure. Actually there a couple of them. You have two different people; one is quite husky and weighs a lot, and the other is petite and doesn’t weigh very much.

The husky one is wearing snow shoes and the petite one is wearing high heels. Would you rather get stepped on by the husky person or the petite person? It turns out that if the petite person stepped on you with their heels, the pressure would be several times bigger than the pressure from the person with the snow shoes on.

This is because in the snow shoe case, you have a lot of force spread out over a large area, so the pressure isn’t as big. In the high heels case we don’t have quite as much force, but it isn’t spread across a large area. In fact, it is concentrated on one little spot–the heel of the shoe. So I would rather get stepped on by the big person wearing snow shoes because it wouldn’t hurt nearly as much.

The concept of pressure is also the reason why people can lie on a bed of nails and not feel any pain. The force from their weight is distributed over a large area, which is the sum of all the individual areas of the tips of the nails.

So this works best if you have a lot of nails, which will provide more area. The more area you have, the less the pressure will be on each nail.