A force is simply a push or pull, but having sizes and directions. Although it seemed simple, force can change the acceleration of an object, therefore changing the speed or direction of the object. When anytime an object is moved, we can make sure that it’s been pushed by a force. The SI (or, official) unit for speed is Newton (N), of course is named after the great scientist who discovered gravity, Sir Isaac Newton!

While we’re typing on a computer, touching the phone, or clicking on a mouse, you’re applying forces to them! Most forces let an object move, while the others don’t. For example, the force you put when you’re sitting on a chair (downwards) didn’t make the chair move. Of course, force couldn’t be seen, and so do airs that are surrounding us. Actually, most forces worked in pairs or more while acting on an object. In order to do that, you need to calculate the “net force,” the combination of all forces, by adding or subtracting the forces (in newtons). If those forces are in the same direction, add them up, and if those forces are in the different direction, subtract them.

By the way, nearly all forces are unbalanced, so an object moves. If forces are given to an object but it didn’t move, that means that the forces are balanced and the net force is at 0 N.