without a relative force can we say there is friction ? is frictional force present all the time ??

Question

without a relative force can we say there is friction ?   is frictional force present all the time ??

anonymous · Answer

absence of relative force implies that friction is not preset. If frictional forces were possible in the absence of relative forces then every body would start moving on its own due to force of friction and no counter applied force balancing friction

anonymous · Answer

I forget the formulae, but there is STATIC FRICTION, which exists between 2 bodies not in relative motion. Static friction is a quantity dependent on the relative force between the two bodies. Therefore, if there is no relative force, the amount of static friction is 0.

The other 2 types of friction -- KINETIC and ROLLING would not apply since they are only applicable when the 2 bodies are in motion with each other. And in this case, there is obviously relative force between them.

anonymous · Answer

If you think of a brick sitting on an inclined plane. Until the angle of the plane is sufficient that friction is overcome by the resolved gravitational force, there is no movement but there is still friction - because therre is a force which is the gravitational force. So a static body experiences friction because there is a force. it is the force not the movement that determines whether there is friction. No force? Then no friction.