An object with a mass of $8 kg$ is on a plane with an incline of $- pi/12$ . If it takes $12 N$ to start pushing the object down the plane and $9 N$ to keep pushing it, what are the coefficients of static and kinetic friction?

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Answer 1 · 2017-05-14T14:29:25

I assume that the angle of inclination is $pi/12$ instead provided ,
we know for that

enter image source here

from the FBD diagram we can conclude that

$f_("static")=mgmucostheta$

$f_("dynamic")=mgmusintheta$

substituting the values you can get your answer (here a in the image is the angle you provided)

$mu_("static")=f_("static")/(mgcostheta)$

$mu_("dynamic")=f_("dynamic")/(mgsintheta)$

An object with a mass of 8 kg8 kg is on a plane with an incline of - pi/12 - pi/12 . If it takes 12 N12 N to start pushing the object down the plane and 9 N9 N to keep pushing it, what are the coefficients of static and kinetic friction?