Q. 2:      ms is larger.

 

It is more difficult to get something to move than it is to keep it moving. 

 

An ideal graph of friction force verses applied force looks like this:

 

 

The values of the coefficients depend on the nature of the surfaces, but typical values range from around 0.03 to 1.0.  He is a list of some reported values:

 

                                                                                  Coefficients of Friction                           

                                  

 

ms

mk
Steel on steel 0.74 0.57
Aluminium on steel 0.61 0.47
Copper on steel  0.53 0.36
Rubber on dry concrete 1.0 0.8
Rubber on wet concrete 0.7 0.5
Wood on Wood 0.25 - 0.5 0.2
Glass on Glass 0.94 0.4
Synovial joints in Humans 0.01 0.003

 

 

 

 

 

 

 

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