I was reading a post in the homework section about friction being able to do positive work. Several people provided examples, and one was the case of a car. Doc Al pointed out that static friction did not do any work on the car because the wheel was not slipping and the friction force acted over no distance. However, I disagree, or more likely I fail to see, his reasoning. Its true that the wheel is not slipping, thats why the friction is static. But I dont agree that it acts over no displacement. At every instant, or snapshot so to speak, on the free body diagram of the car, static friction is acting forwards in the direction of motion of the car. Thus static friction HAS to be doing positive work on the car, no? Im not saying that the static frictional force is giving energy to the car, because its not. I said that it transfers energy, to which Andrew Mason did not like my wording, I believe he called it a mechanical link of energy. Well, I appreciate your help. I have a few more cases about friction I will ask, so please try not to anwser my question with another example of friction doing work on a different body. At this time all I care about in particular is the case of the car. (Im sorry if im misquoting Andrew or Doc).