Question

A mass of $4kg$ rest on the horizontal plane. The plane is gradually inclined until at an anger of $\theta ={15}^o$ with the horizontal, The mass just begin the block & the surface

Answer 1

$mg\sin 15=kmg\cos 15$

$k=\tan 15=\tan (45–30)$

$k=\frac{\tan 45–\tan 30}{1+\tan 45\tan 30}=\frac{\sqrt{3}-1}{\sqrt{3}+1}$