question_answer

Mass of block A is 10 kg. Coefficient of friction between the block A and surface is 0.3. What is the maximum values of M for which system remains in equilibrium  \[\left( g=10m/{{s}^{2}} \right)\]

A) 2 kg                             

B) 6 kg

C) 3 kg     

D) 5 kg

Correct Answer: C

Solution :

Maximum friction force between block A and surface is:

\[{{f}_{_{\max }}}=\mu mg=\left( 0.3 \right)\left( 10 \right)\left( 10 \right)=\,\,30\,N\]

Therefore, maximum tension in the string connected with block A should be 30 N.

Now,

\[T'\cos \,45{}^\circ =30\]           ...(1)

\[T'sin\,45{}^\circ =Mg\]             ....(2)

From equations (1) and (2), M = 3 kg