Explanation

• Kinetic friction (fk) is the frictional force that acts on an object when it is already moving, whereas static friction (fs) is the frictional force that prevents an object from moving when a force is applied to it.
• The relationship between kinetic friction and static friction is: fk < fs
• Kinetic friction is always less than static friction because it takes less force to keep an object moving than to start it moving from rest.
• This is because the surfaces in contact have already overcome the initial resistance to motion when the object is moving, making it easier to maintain motion.