Net Force

If several forces act on an object, then we can add all of them to obtain the net force. The net force, _net, which may be the sum of many forces (each of which is labeled by i as _i, i = 1, 2, ... , n) acts as one single force

The individual forces can be:

• Contact forces
  • Examples are: pushing, kicking, lifting, pulling, ...
  • Objects need to be in direct physical contact with each other to exert these kinds of forces on each other.
• Action-at-a-distance
  • Examples are: gravity, magnetism, electrostatic attraction, ... The only one of these that interests us for now is gravity, the other action-at-a-distance forces will only appear in the second semester of this course.
  • These action-at-a distance forces occur when the objects exerting these forces on each other are not in direct contact with each other. Instead these forces are transmitted by exchanging particles. (How this exactly works is not really relevant here and will be discussed in the second semester of this course.)

© MultiMedia Physics, 1999