When finding the Net force, why does the force of friction subtracted by gravity? I would think they would add together since they are moving in the same direction.

Answer 1

Friction and gravity are indeed both forces acting in the same direction, but they are opposing forces. Friction is a force that acts in the direction opposite to the direction of motion or the potential motion of an object. Gravity, on the other hand, is a force that acts in the direction of the object’s weight towards the center of the Earth.

When calculating the net force, we must consider the opposing nature of these two forces. The force of friction is subtracted from the force of gravity because friction is resisting the motion caused by gravity. In other words, friction is working against gravity to slow down or stop the object's motion.

Therefore, when finding the net force, we subtract the force of friction from the force of gravity to determine the overall force acting on the object in the direction of motion.