Block $A$ of mass $100 \ kg$ is kept above another block $B$ of mass $300 \ kg$. Block $A$ is tied to the wall $C$ with a horizontal string. The coefficient of friction between $A$ and $B$ is $0.35$ and that between $B$ and the horizontal surface is $0.5$. Find the horizontal force $P$ necessary to move the block $B$. (in $N$)

Block $A$ weighing $100 \, kg$ rests on a block $B$ and is tied with a horizontal string to the wall at $C$. Block $B$ weighs $200 \, kg$. The coefficient of friction between $A$ and $B$ is $0.25$ and between $B$ and the surface is $1/3$. The horizontal force $P$ necessary to move the block $B$ should be ........ $N$ $(g = 10 \, m/s^2)$.

Two blocks $A$ and $B$ of masses $m_A = 1\,kg$ and $m_B = 3\,kg$ are kept on a table as shown in the figure. The coefficient of friction between $A$ and $B$ is $\mu_1 = 0.2$ and between $B$ and the surface of the table is $\mu_2 = 0.2$. The maximum horizontal force $F$ that can be applied on $B$ such that block $A$ does not slide over block $B$ is ........ $N$. [Take $g = 10\,m/s^2$]

Three blocks $A$,$B$,and $C$ of equal mass $m$ are placed on a smooth surface as shown. The coefficient of friction between any two blocks $A$,$B$,and $C$ is $\mu$. The maximum value of mass $M$ of block $D$ such that blocks $A$,$B$,and $C$ move without slipping over each other is:

Two blocks $A$ and $B$ of masses $6 \, kg$ and $3 \, kg$ rest on a smooth horizontal surface as shown in the figure. If the coefficient of friction between $A$ and $B$ is $0.4$,find the maximum horizontal force $F$ that can be applied to block $A$ such that they move together without separation. (in $, N$)

When $F = 2 \, N$,the frictional force between the $5 \, kg$ block and the ground is $.......... \, N$.