Explain Force Diagrams and Addition of Forces

If you have a piano and your friend offers to help move it, would it be more helpful for him to push with 100 Newtons on the side opposite from where you are pulling the rope attached to the piano with 150 Newtons or push on the same side as you are pulling? A vector diagram of the forces can quickly give you an answer to this question. It helps you visualize whether the forces are in the same direction or in opposite directions. If the forces are in the same direction, the resultant of the vector addition is bigger, 150N + 100N = 250N. If the forces are in the opposite directions, then they partially work to cancel each other, you must subtract one force from the other so that the resultant vector is smaller:150N - 100N = 50 N. A free body diagram will help you to make sure you do the correct addition or subtraction problem. A free body diagram illustrates one point along a line that connects two force vectors. The tails of the vectors meet at this point.