An object with a mass of 10 kg is on a plane with an incline of - pi/4 . If it takes 12 N to start pushing the object down the plane and 7 N to keep pushing it, what are the coefficients of static and kinetic friction?

1 Answer
Mar 9, 2018

mu_s = 0.173
mu_k= 0.101

Explanation:

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pi/4 is 180/4 deg = 45 degrees

The mass of 10Kg on the incliine resolves to a 98N force vertically.
The component along the plane will be :

98N * sin45 = 98 * .707 = 69.29N

Let the static friction be mu_s

Static Friction force =mu_s* 98 * cos 45 = 12

mu_s = 12/(98*0.707) = 0.173

Let kinetic friction be mu_k

Kinetic Friction force =mu_k* 98 * cos 45 = 7

mu_k= 7/(98*0.707) = 0.101