(a) Define frictional force (or friction)
(b) Explain why frictional force is said to be a contact force.
(c) Explain why magnetic force is said to be a non-contact force.
(a) Define frictional force (or friction)
(b) Explain why frictional force is said to be a contact force.
(c) Explain why magnetic force is said to be a non-contact force.
(a) Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other. Dry friction is subdivided into static friction ("stiction") between non-moving surfaces, and kinetic friction between moving surfaces.
(b) The frictional force always acts on all the moving objects and its direction is always opposite to the direction of motion. Since frictional force arises when the surface of two objects are in touch with each other ,therefore, frictional force is an example of contact force.
(c) There is a magnetic force that exists between two opposite magnetic poles that can actually bring them together even when the poles are far apart, it is easy to say that it is a non-contact force.
(a) Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other. Dry friction is subdivided into static friction ("stiction") between non-moving surfaces, and kinetic friction between moving surfaces.
(b) The frictional force always acts on all the moving objects and its direction is always opposite to the direction of motion. Since frictional force arises when the surface of two objects are in touch with each other ,therefore, frictional force is an example of contact force.
(c) There is a magnetic force that exists between two opposite magnetic poles that can actually bring them together even when the poles are far apart, it is easy to say that it is a non-contact force.
