Two masses A and B of 10 kg and 5 kg res

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Two masses $A$ and $B$ of $10\, kg$ and $5 \,kg$ respectively are connected with a string passing over a frictionless pulley fixed at the corner of a table as shown. The coefficient of static friction of $A$ with table is $0.2$. The minimum mass of $C$ that may be placed on $A$ to prevent it from moving is ........ $kg$

A

$15$

B

$10$

C

$5$

D

$12$

Two masses $A$ and $B$ of $10\, kg$ and $5 \,kg$ respectively are connected with a string passing over a frictionless pulley fixed at the corner of a table as shown. The coefficient of static friction of $A$ with table is $0.2$. The minimum mass of $C$ that may be placed on $A$ to prevent it from moving is ........ $kg$

For limiting condition $\mu = \frac{{{m_B}}}{{{m_A} + {m_C}}}$  $⇒$ $0.2 = \frac{5}{{10 + {m_C}}}$

$⇒$  $2 + 0.2{m_C} = 5$  $⇒$  ${m_C} = 15\,kg$