 Now there are some very common misconceptions that people fall into when they look at Newton's third law. The first is when a big thing interacts with a small thing that the big thing applies a bigger force. For example, if you step on a blade of grass then yes, there's a very large force on that blade of grass from your body weight. But in fact, there's an equal and opposite force from that blade of grass up on you. But even though that force is equal, the same force will do a lot more to a blade of grass than it will do to a foot. And so the real way this works is that big things respond to forces less sensitively than small things. The next misconception is that a force is something that an object can have. For example, a big magnet people might say has a big magnetic force, or the earth they might say has a large gravitational force. But the reality is that all forces come in pairs and they're the interaction between two objects. So a big magnet doesn't have a big force. A big magnet and something else can exert an equal and opposite force on each other, which may or may not be big. And similarly the earth doesn't have a large gravitational force. The earth and some other mass together can exert a mutual equal and opposite gravitational force on each other. The third misconception is that balanced forces on an object exist because of Newton's third law. So for example, if I'm standing on the earth and there's a force of gravity on me, pulling me down, and there's a force due to the ground pushing me up. It's often called the normal force. And the fact that I'm neither accelerating up into the sky nor down through the earth means that the normal force is exactly equal and opposite to the gravitational force, and that's why I stand still. But those are not the Newton's third law equal and opposite forces because they're both acting on me. In fact, they come from two different interactions. The interaction from the gravity is because of the existence of the earth, and it's enormous mass, and me. It's a gravitational attraction between me and the earth. So the equal and opposite force from Newton's third law for that is my pull on the earth. So I'm pulling the earth up gravitationally just as the earth is pulling me down. And the interaction for the normal force is the existence of the ground. If I was instead standing on water, then I would find that the gravity would indeed accelerate me downwards. And so the Newton's third law pair for that is my force on the ground. If I was standing on thin ice, then that force would break the ice. And so the normal force is about the interaction between me and the actual surface I'm standing on, and the gravitational force is between my mass and the earth's mass. So because Newton's law describes forces on two objects, and there's only ever one of those forces on each object, they can never balance. So they never balance on an object. If they could, then what Newton's third law would be saying is that there's always an equal and opposite force on that same object, and so there'd be no such thing as force. They'd always cancel. But they don't always cancel. If I'm pushing on someone, someone's pushing on me, we both get pushed. We get pushed in equal and opposite directions, but there's definitely pushing happen on each of us.