So how much of a given force is in the direction of the displacement? (We could consider the equivalent description of the amount of the displacement in the direction of the force.) Therefore, \(-F_{\...So how much of a given force is in the direction of the displacement? (We could consider the equivalent description of the amount of the displacement in the direction of the force.) Therefore, −Fk frictionΔx is not the work done on the block by friction: −Fk frictionΔx is the total work done by friction (done on the block and the table) and is the amount that the kinetic energy is reduced.
