---- Mike Spalding <mike.spalding1 at verizon.net> wrote: > Frank, I'd like to understand what you're saying; could you clarify > please? If there is no sliding friction, then what kind of friction is > it? Do you mean to say that the parts do not slide, or that they slide > with no friction? If there is sliding there most certainly is friction. If you have two wheels at the end of two lever arms, they can roll together, without sliding, to arrive at a new position. If one travels along the other the same distance as the other travels along the former, there is no sliding, only rolling. When I drive my car down the road, the tires roll on the pavement. There is no sliding friction, but there is some friction, to be sure, between the tires and the road, and between the vehicle and the air surrounding it. If I slam on my breaks to avoid an accident, sliding friction is introduced, and significantly adds to the friction quotient (Thank God!). Likewise, if a capstan can roll on the surface of the wippen heal , and the wippen heal can roll on the surface of the capstan the same distance, there is no sliding involved, only rolling. The leverage ratio is changing throughout the motion, but sliding friction is not necessarily involved. Frank Emerson
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