Question #31590

1 Answer
Oct 24, 2016

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Forces acting on the body are shown in the diagram above

Sum of the forces along the inclined plane:
F_"net" = mg sin theta -f Fnet=mgsinθf
where mgmg is the weight of the body and ff is force of friction.

There is no acceleration along the inclined plane, F_"net" = 0Fnet=0, therefore
mg sin theta =f mgsinθ=f ......(1)

Similarly in a direction perpendicular to the inclined plane:
F_"net" = N -mg cos thetaFnet=Nmgcosθ
where NN is normal reaction.

As per given condition above there is no acceleration in this direction either, F_"net" = 0Fnet=0, and therefore
N =mg cos thetaN=mgcosθ ......(2)

If mu_kμk is coefficient of kinetic friction, then
f = µ_kN

Using (1) and (2) we get
mg sin theta=mu_kxxmg cos theta

Solving for mu_k
mu_k=tan theta
mu_k=tan 30^@=1/sqrt3