I am currently working on an experiment to find the kinetic friction in a driveline. The experiment uses the principle of conservation of energy and is based on the following experiment: http://hyperphysics.phy-astr.gsu.edu/HBASE/Class/PhSciLab/frictionex.html The difference in my proposed experiment is that instead of having the sliding block on the table, there would basically only be the pulley and a line would be wrapped completely around the pulley attached to a weighted system. The initial energy balance would still be the potential energy of the hanging mass, and a withdrawal from the system would be the mass hitting the floor and losing kinetic energy. In the experiment in the link, the rest of the energy is said to go to the sliding block (assuming a frictionless pulley i'm guessing). My question is can the same methodology be used to calculate the friction in the pulley in the case of my experiment (no sliding block)? ie. Would the rest of the energy in the system, assuming it is kinetic friction keeping the mass from free falling at g, be equal to some frictional force over some distance?