What is the definition of work done against friction?

The definition of work done against friction involves understanding the relationship between the frictional force and the distance over which that force acts. Work is calculated as the product of force and the distance moved in the direction of that force. When considering friction, the work done against friction can specifically be defined as the magnitude of the frictional force multiplied by the distance over which that force acts.

In this context, the frictional force opposes the motion of an object, and the work done against friction is a measure of the energy that must be expended to overcome this resistance. Therefore, the correct option reflects the fundamental relationship in physics where work is the product of force and displacement, which in this case is specifically the frictional force and the distance moved in the direction opposing that force.

This concept is essential in understanding energy transformations during motion, particularly as it relates to the work-energy principle. The other options do not accurately capture the specific definition of work done against friction as they refer to different physical relationships, such as distance alone, energy changes without specific reference to forces, or mass and acceleration, which are unrelated to the act of doing work against friction.