Balanced or Unbalanced?
Today in class we mainly worked on white boards and drew more FBDs on them! We did not take many notes, we just redrew what we drew during class and discussed topics. We also got a little work sheet as well. Before I get into the main part of the post, let me explain what a balanced force is and what an unbalanced force is, we learned a lot of other things today too, but balanced and unbalanced is what we are really worried about here.
A balanced force is when two opposing forces when added and/or subtracted equal zero. Balanced forces have a net force of zero and are equivalent. A balanced force, for example, is gravity downward with a magnitude of 5 and normal force upward with a magnitude of 5. They are both the same so therefore when subtracted they equal 0. Forces can also be broken up into separate lines on certain sides I believe so you must count even Newton on one side. Balanced forces usually keep an object at rest.
An unbalanced force has a net force that does not equal zero and cause objects to move usually. These forces are not equivalent; they have different magnitudes. Also, keep in mind we're talking about opposing forces. An example of unbalanced force would be 10 N up and 5 down. The net would be 5 which of course does not equal zero. Therefore it is an unbalanced force. Think of scales when you hear these classifications.
Let's begin with an unbalanced diagram. This FBD has four forces acting on it as you can see (normal, friction, gravitational, and applied). The first force that we always label first, gravity, is the force going downward and is the force opposing normal force. Normal force comes after that as the item is probably on a surface and must oppose gravity (also probably because the object is not accelerating downwards). Both normal force and gravitational force are equal in magnitude here. So why is this diagram not balanced? Well, the reason why is because even though the net force of gravity and normal force is zero, there are two other forces that have a net force that does not equal zero; friction and applied force. The applied force is the force going right and friction is going in the opposite direction as with all opposing forces. Both forces have different magnitudes though as the arrow length indicates. Since they have different magnitudes there will be a net force, and balanced forces have a net force of zero. Even though only one set off forces has a net force, the diagram is still unbalanced. Really what makes this unbalanced is friction and the applied force and the net force will cause the object to move most likely. It is the difference in magnitude and the opposing directions that cause it too. Unbalanced diagrams will have non equivalent magnitudes with opposing forces basically.
This is a balanced FBD. But before I explain why, I shall describe the forces acting on the body above. The forces here are friction, applied, gravitational, and normal. Each force is of the same magnitude, the only difference is the direction each force is going. Gravity is going down, normal is going up, applied is going right, and friction is going left. Since the object is balanced it is at rest. Now, since the forces are of the same magnitude there is no net force when subtracted and when the net is zero it is balanced. And each opposing set of forces are the same size, due to that this is balanced. And it does not matter if the forces were broken into two arrows or something, if the magnitude when added up for one side is the same it will still work as the same amount of force is being applied.
Good night everyone, I suck but have bunnies <3
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