Hi, I'm going to be showing you how to draw a simple free body diagram. A correct and complete free body diagram includes the following characteristics. It includes a type for every force, so weight force is a type, friction force is a type. Usually there's a special symbol associated with the type that you write down. Then after the type you include some subscripts, the first subscript would be the source of the force, the external entity that is directly acting upon the object in question. We put that as your first subscript. And then the receiver of the force, the object that you're drawing the free body diagram for, who is the force exerted upon? That would be the receiver with the second subscript. Then we draw an arrow indicating the direction and approximate magnitude of the force. So direction, just an arrow indicating the direction that you think the force is being exerted. And then we use the term approximate relative magnitude when we're talking about free body diagrams. That just means if we know that the force is very strong, then we draw a long arrow if the force is weak, then we draw a short arrow. OK, so using these principles, let's go ahead and draw a free body diagram for me right here, right now. So you can pause the video if you like. You can try this yourself, and then you can compare your work to mine. OK, so typically when I'm drawing a free body diagram, I start with the weight force. So the weight force is exerted by the earth. So I use a special symbol W for weight force, weight force exerted by the earth on me. So some people also call this the gravitational force. That's fine too. They're really synonyms. And then we draw an arrow straight down indicating that the earth is pulling me towards the center of the earth. And so thinking about the physical situation, I'm just standing here more or less at rest. And so there must be something counteracting the weight force. So there is I would plummet towards the center of the earth. That thing that's preventing me from plummeting the center of the earth is the floor. So there is a normal force exerted by the floor. So the floor is horizontal, and the term normal just means perpendicular. The normal force is both perpendicular and repulsive. So it's an upward force. So normal force exerted by the floor on me. And so notice that the second subscript here is always the same. So I'm drawing a free body diagram for me. So all the subscripts will be, second subscripts will be M. OK, and that normal force has to be equal and opposite from the weight force. Otherwise, there would be a net force up or down, and I would accelerate up or down. But I'm not. So I draw an arrow roughly the same length as the weight force showing that the vector some of these forces is zero. OK, so that's it for this particular free body diagram. Next time we'll try something a little bit more complicated.