Final answer:
The kinetic coefficient of friction is a ratio that represents the frictional force opposing the motion of a sliding block on a horizontal surface and is used to calculate the magnitude of this force.
Step-by-step explanation:
The kinetic coefficient of friction, often denoted as μ_k, refers to the ratio of the kinetic frictional force between two surfaces in relative motion to the normal force pressing them together. In the context of a block of mass m sliding on a horizontal surface, the kinetic coefficient of friction is used to calculate the frictional force that resists the slide of the block.
It is independent of the relative speed of the surfaces and does not change for different velocities of the sliding object. Considering a kinetic coefficient of friction μ_k and a block of mass m the kinetic frictional force (F_k) can be calculated by F_k = μ_k × normal force (N). As the block slides on a horizontal surface, the normal force is equal to the gravitational force acting on the block (mg), hence F_k = μ_k × mg. The kinetic frictional force acts opposite to the direction of the block's motion and affects its acceleration.