Final answer:
Friction does not depend on speed; it only opposes motion. Force and acceleration are directly proportional through Newton's Second Law, with acceleration also inversely proportional to mass. Drag force can be proportional to velocity or the square of velocity, especially relevant for larger, faster-moving objects.
Step-by-step explanation:
The relationship between friction and speed is often misunderstood. The magnitude of the coefficient of kinetic friction is generally considered to be independent of the relative motion speed (option C), meaning the friction coefficient does not inherently increase or decrease with the speed of the objects in contact. When friction becomes large enough, it can prevent an object from starting to move, but it does not cause an object to move in the opposite direction. In terms of the relationship between force and acceleration, Newton's Second Law of Motion explains that acceleration is directly proportional to the net force applied to an object and inversely proportional to its mass (a = Fnet/m). This means that as force increases, acceleration increases, provided that the mass of the object remains constant.
For drag forces, we see two expressions. Drag force opposing the motion of an object in a fluid can be proportional to the velocity or to the square of the velocity of the object. The latter is often applicable to larger objects moving at higher speeds, as the drag becomes more significant with increasing velocity.