An object with a mass of 2 kg2kg is on a ramp at an incline of pi/12 π12. If the object is being pushed up the ramp with a force of 8 N8N, what is the minimum coefficient of static friction needed for the object to remain put?

1 Answer
Jun 3, 2018

mu = 0.155μ=0.155

Explanation:

we can write pi/12π12 as 15° in degree.
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Now please consider the image and look at the free body diagram and the forces acting on it.

8N8N force acting upwards and mgsinthetamgsinθ, mu mg costhetaμmgcosθ downwards. where the muμ is coefficient of static friction, mm is mass and gg is accelaration due to gravity.

Thus for the object to be put,
rArr 8N = mgsintheta + mu mgcostheta8N=mgsinθ+μmgcosθ

rArr (8 - 2*9.8*sin15°)/(2*9.8*cos15°) = mu

as sin15°=0.256 and cos15°=0.998

after calculation mu= 0.155

Hence coefficient of static friction is mu = 0.155