Newton's Laws Legacy Problem #11 Guided Solution

The diagram that you see at the right is known as a free body diagram. It provides a visual representation of the forces, or the pushes or pulls, which act up on our bag of grass. Each force is represented by an arrow, and the arrow points in the direction of the force. Each arrow is labeled with a label that tells you what type of force it is. You can read more about these types of forces by using the link to the physics classroom that you see below this question. Now what we're to do here is determine the net force. The net force is simply the vector sum of all the forces. Meaning you simply add up all the force values, treating them as vectors which have a direction. When you add vectors, you add them differently than when you add scalars. For instance, 5 plus 5, to most of us, is equal to 10. But to the physics student, 5 plus 5 could be equal to 0. Or any other number that you could get when you add 5 plus 5 as vectors. It could be equal to 0 if the two 5's are going in opposite directions. You would treat 1 as negative and add it to the positive. So in this problem, we notice the Fgrav, that's gravity force, and the Fnorm, or normal force, are of the same size and going in opposite directions. So they would add up to 0. That leaves us with two more forces to add together. The applied force, F-amp, and the friction force, F-frict. We have to add these as vectors. One goes 40.2 newtons to the right, and the other 5.7 newtons to the left. So the way to add such vectors is to call the left one negative, and then add the negative value onto the positive right one. So you're going 40.2 plus negative 5.7.