Respuesta :
I think that the answer is 2.the force that opposes the relative motion of two objects in contact with and sliding past each other.
Answer:
2. the force that opposes the relative motion of two objects in contact with and sliding past each other
Explanation:
Consider a body supported on a horizontal and rigid surface. If the body receives the action of a force f, due to the roughness, the frictional force appears.
Frictional forces are contrary to movement. There are two types of static and kinetic friction. When there is force acting on a body but it does not move, friction is called static, when there is force acting on a body and it moves, friction is called kinetic. In general, we can say that friction is the force that opposes the relative movement of two objects in contact and sliding one after the other.