A body of mass 2kg rests on a rough inclined plane making an angle \[{{30}^{o}}\] with the horizontal. The coefficient of static friction between the block and the plane is\[0.7\]. the frictional free on the block is:
A) \[9.8\,N\]
B) \[0.7\times 98\times \frac{1}{\sqrt{3}}N\]
C) \[9.8\times \sqrt{3}\]
D) \[0.7\times 9.8\,N\]
Correct Answer:
A
Solution :
From the figure. \[{{F}_{S}}=\mu mg\,\cos \theta =0.7\times 2\times 9.8\times \sqrt{\frac{3}{2}}>9.8\] \[{{F}_{S}}=mg\,\sin \theta =9.8\] Here, \[\theta ={{30}^{o}}\]