If you are holding a dumbbell in your hand, there are three forces acting, Weight of the arm pulling the arm down, a tension force that the muscle in the shoulder exerts on the arm, and the force that the dumbbell exerts on the fist.. which of these forces are contact forces?

some help would be appreciated!

1 answer

Since all the objects and the muscles are touching each other to apply a force, all three are contact forces.
Non-contact forces can be applied at a distance, such as force of gravity, magnetic forces, etc.
See also:
http://en.wikipedia.org/wiki/Contact_force