Final answer:
To turn static coefficient of friction into kinetic, one must apply a force greater than the product of the static friction coefficient and the normal force to initiate movement. Once an object is moving, the kinetic coefficient of friction determines the force needed to maintain constant velocity.
Step-by-step explanation:
The process of turning the static coefficient of friction into the kinetic coefficient of friction involves understanding when each coefficient applies.
The static coefficient of friction (μs) is applicable when the two surfaces in contact are not moving relative to each other.
For motion to start, one must overcome the maximum static friction force, which is calculated as fs(max) = μsN.
Once motion has begun, the kinetic coefficient of friction (μk) comes into play, which is typically less than μs.
The kinetic friction force (f) that keeps the object moving at a constant speed is calculated as f = μkN.
For instance, if a crate has a static coefficient of friction of 0.45, a force greater than 440 N, which is the product of the static coefficient and the normal force (N), must be applied to initiate movement.
Once the crate is in motion, a continuous force based on the kinetic coefficient of friction of 0.30 and normal force, resulting in 290 N, would be required to keep it moving at a constant velocity.