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Peter Frauenglass		 How would you determine friction of a needle point spinning on a surface? View All
Assuming it's in a vacuum, and any other needed information is already known (constants of friction, weight resting on the needle, etc). Can it be done otherwise than experimentally?
1 month ago - 10 months left to answer. - 1 response - Report Abuse
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richie
 Static frictional forces from the interlocking of the irregularities of two surfaces will increase to prevent any relative motion up until some limit where motion occurs. It is that threshold of motion which is characterized by the coefficient of static friction. The coefficient of static friction is typically larger than the coefficient of kinetic friction.
In making a distinction between static and kinetic coefficients of friction, we are dealing with an aspect of "real world" common experience with a phenomenon which cannot be simply characterized. The difference between static and kinetic coefficients obtained in simple experiments like wooden blocks sliding on wooden inclines roughly follows the model depicted in the friction plot from which the illustration above is taken. This difference may arise from irregularities, surface contaminants, etc. which defy precise description. When such experiments are carried out with smooth metal blocks which are carefully cleaned, the differe

1 month ago

Source: http://hyperphysics.phy-astr.gsu.edu/hbase/frict2.html#sta


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