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derive expressions for the static and kinetic coefficients of friction using any

ID: 1899919 • Letter: D

Question

derive expressions for the static and kinetic coefficients of friction using any terms relevant to the situation (e.g., applied force, normal force, acceleration of gravity, mass, angle of incline). .


Block Pulled on Flat Surface
(a) Place a friction block fuzzy side down on a track and add some mass on top to give it extra traction. Pull the block VERY SLOWLY with a spring scale, starting with very little effort but continuously increasing your effort over a few seconds until the block suddenly slips, and then continuing for another second or two with the block sliding at constant speed.

Explanation / Answer

sliding down a ramp at constant speed means that Fp = Ff Fp = Fw sin(theta) Ff = mu(k) Fn Fn = Fw cos(theta) Ff = mu(k) Fw cos(theta) so mu(k) Fw cos(theta) = Fw sin(theta) cancel Fw and rearrange mu(k) = sin(theta) / cos(theta) = tan(theta)