Final answer:
Static friction, or friction at rest, is the type of friction that reaches its maximum before an object begins to move. Once the object is moving, kinetic friction acts on it, requiring less force to maintain motion.
Step-by-step explanation:
The friction between an object and the floor that reaches its maximum value to break loose or to make the object about to move is known as static friction or friction at rest. This type of friction is a responsive force that increases to match the applied force, up to its maximum limit. Once this limit is exceeded, the object will move, transitioning to kinetic friction, which is typically a lower value and acts on an object in motion. For example, if you have a crate with a mass of 100 kg and a coefficient of static friction of 0.45, a force greater than 440 N would need to be applied parallel to the floor to overcome static friction and start movement. Once moving, kinetic friction governed by a lower coefficient will continue to oppose the motion but will require a smaller force to maintain constant speed.