ELI5: Explain Like I'm 5

Cremona diagram

A Cremona diagram is a way of drawing a line on paper to show how much force is being used in different directions. Think about playing with a toy car that you push forward with your hands. Your hands are pushing in one direction and the car moves that way. But what if you push it sideways or at an angle? The car might not move as quickly or might even change direction.

The Cremona diagram is kind of like a map that shows the different strengths of all the forces being used to move the car in different directions. It starts with a square and lines coming out of each corner that show different forces being applied. The forces are drawn as arrows, pointing in the direction that the force is being applied. The longer the arrow, the stronger the force.

When you add up all the forces that are pushing the toy car, you can see on the Cremona diagram where it will end up moving. This is because the diagram shows the 'resultant force', which is the total of all the forces being used.

So if you're trying to move the toy car straight ahead, you need to make sure your hands are pushing in the same direction with the same amount of force. Otherwise, the Cremona diagram will show that the forces are not balanced, and the car might end up moving in a different direction than you intended.

In short, a Cremona diagram is a way of drawing and understanding the forces involved in movement, like when you're playing with a toy car or pushing a playground swing.