Question

If the mass of $A=10 \, kg$ , coefficient of static friction $=0.22,$ coefficient of kinetic friction $=0.2,$ then minimum mass of $B$ to start motion is

• A. $2kg$
• B. $2.2 \, kg$
• C. $4.8kg$
• D. $3.4kg$

Answer 1

Answer: (B)

Let the minimum mass of B is $M_{B}.$
Force applied by it $F=M_{B} \, g$
Friction force on block $A$
$f=\mu \, M_{A} \, g$
For motion to start
$M_{B} \, g=\mu \, M_{A} \, g$
$M_{B}=0.22\times 10$
$=2.2 \, kg$