Question

Two masses $A$ and $B$ of $10kg$ and $5kg$ respectively are connected with a string passing over a friction less 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

• A. $15kg$
• B. $10kg$
• C. $5kg$
• D. $12kg$

Answer 1

The correct option is A $15kg$

Since for $B$

$\therefore Mg=T$

$=5g=T$

For $AC$

$(10+m)g\mu =T$

$\therefore 5g=(10+m)g\mu$

$5=(10+m)\left(0.2\right)$

$5=2+0.2m$

$3=0.2m$

$m=15Kg$