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This might seem like a stupid question, but my instructor could not give a straightforward answer.
If a body is kept in contact with a completely vertical surface i.e. right angle to the ground, and only force on the body is the force of gravity straight downwards.Then normal force on the body would be zero. We know that frictional force on the body is proportional to the normal force, hence it is also zero. Does that mean there is no friction whatsoever, despite the surface rubbing?