The correct answer is option 4 i.e Smaller
Friction Force: It is a kind of resisting force that acts between two contact bodies to avoid relative motion between them.
Static friction acts on objects when they are resting on a surface. It must always be overcome to start a body moving.
Sliding friction term refers to the resistance created by two objects sliding against each other. This can also be called kinetic friction. Sliding friction is intended to stop an object from moving.
Rolling friction is friction that acts on objects when they are rolling over a surface. Rolling friction is much weaker than sliding friction or static friction.
ΜRolling < μSliding < μStatic
μr < μk < μS
Explanation:
The sliding friction is less or smaller than static friction because of the interlocking of irregularities in the two surfaces. When the object starts sliding, the contact points on its surface do not get enough time to lock into the contact points on the floor. So the sliding friction is slightly less than the static friction.
If a very gentle force in the horizontal direction is given to an object it does not move. It is because of the opposing force exerted by the surface on the object which resists its motion.
This force is called the frictional force which always opposes the relative motion between an object and the surface where it is placed. If the force applied is increased, the object moves after a certain limit.
Static friction is the force that opposes the initiation of motion of an object on the surface. When the object is at rest on the surface, only two forces act on it. They are the downward gravitational force and upward normal force. The resultant of these two forces on the object is zero.
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