question_answer

A uniform disc of radius R and mass m is connected to a wall by string of length 2R. The normal reaction of wall is

A)  \[mg\]                          

B)  \[mg/2\]

C)  \[mg/\sqrt{3}\]              

D)  \[2mg\]

Correct Answer: C

Solution :

 \[mg=T\,\cos \,{{30}^{o}}\] \[N=T\,\sin \,{{30}^{o}}\] \[\Rightarrow \] \[N=\frac{mg}{\sqrt{3}}\]