Question

The coefficient of static friction, $\mu _{s} ,$ between block $A$ of mass $2kg$ and the table as shown in the figure is $0.2$ . The maximum mass value of block $B$ so that the two blocks do not move is (The string and the pulley are assumed to be smooth and massless $g=10\,ms^{- 2})$

• A. $0.4 \, kg$
• B. $2.0 \, kg$
• C. $4.0 \, kg$
• D. $0.2 \, kg$

Answer 1

Answer: (A)

Condition for not moving the block is that the tension in the string should be equal to static frictional force, here tension will be equal to $m_{B}g$
$ \, \, m_{B} \, g=\mu _{s} \, m_{A} \, g \\ \Rightarrow \, m_{B}=\mu _{s} \, m_{A} \\ or, \, \, \, m_{B}=0.2\times 2=0.4 \, kg$