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## Homework Statement

Let F , F

_{N}and f denote the magnitudes of the contact force , normal force and the force of friction exerted by one surface on the other kept in contact. If none of these is zero , then ,

(A.) F>F

_{N}

(B.) F>f

(C.) F

_{N}>f

(D.) F

_{N}-f<F<F

_{N}+f

## Homework Equations

Well , I don't know whether object is moving with respect to other or not...

In case of static friction ,

f

_{s}≤ μ

_{s}F

_{N}

In case of kinetic friction ,

f

_{k}= μ

_{k}F

_{N}< μ

_{s}F

_{N}

## The Attempt at a Solution

http://postimage.org/image/yqh9rg6pl/ [Broken]

OK , So obviously (A) is correct. (B) is also correct. (D) obviously is correct. (C) is also correct as it would mean that tanθ = μ <1 which is also true.

So I go for A , B , C , D. But the textbook gives the answer A,B,D. Why is it so ? Where am I going wrong ?

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