Notice that there is a different coefficient for static and kinetic (sliding) friction. On to the first experiment (using the DIY force scale). Here I have a block on a table.

Friction is a contact force when two surfaces interact. The second equation is the kinetic frictional force that is used when two surfaces are sliding against each other.

Since 1987, MCEER, formerly the Multidisciplinary Center for Earthquake Engineering Research (MCEER) and the National Center for Earthquake Engineering Research ( NCEER), has produced over 600 ...

Say we consider a simple experiment of balancing a wooden rod on two fingers. The finger on the left, (1), will remain stationary, whereas the finger on the right, (2), will be moved toward the left.