The discussion centers on the relationship between kinetic friction (fk) and static friction (fs), specifically why fk is less than or equal to fs. Participants explain that an energy threshold must be overcome to initiate movement between surfaces, which can be visualized as interlocking ripples on the surfaces. This concept is further supported by the comparison of coefficients of friction, where the coefficient of kinetic friction (μk) is always less than or equal to the coefficient of static friction (μs). The discussion references educational resources, including Khan Academy, to illustrate these principles.
PREREQUISITESStudents of physics, educators teaching mechanics, and anyone interested in understanding the principles of friction and its applications in real-world scenarios.
I looked at that, but unfortunately there's about as much misinformation as worthwhile comments there. And I couldn't find any that match what I've always taken to be the explanation: that there's an energy threshold to be overcome.tolove said:
haruspex said:I looked at that, but unfortunately there's about as much misinformation as worthwhile comments there. And I couldn't find any that match what I've always taken to be the explanation: that there's an energy threshold to be overcome.
Imagine e.g. that the two surfaces are made of materials which, if completely flat, would have no friction at all. But instead of being flat, each consists of parallel ripples. At rest, the two sets of ripples interlock. A small amount of energy needs to be invested in lifting the block over the ripples, but that energy is then available to get it over the next ripple, and so on.
It needn't be physical ripples - it could be some electrostatic bonding, but the concept is the same.
So I did a quick search and found this http://www.khanacademy.org/science/...on-on-static-and-kinetic-friction-comparisons
Only that it jibes with what I thought up myself.tolove said:Do you have an idea of how accurate his presentation is?