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 $, N$)

$A$ block $A$ of mass $4\, kg$ is placed on another block $B$ of mass $5\, kg$,and the block $B$ rests on a smooth horizontal table. If the minimum force that can be applied on $A$ so that both the blocks move together is $12\, N$,the maximum force that can be applied to $B$ for the blocks to move together will be ....... $N$.

$A$ system of two blocks of masses $m = 2 \; kg$ and $M = 8 \; kg$ is placed on a smooth table as shown in the figure. The coefficient of static friction between the two blocks is $0.5$. The maximum horizontal force $F$ that can be applied to the block of mass $M$ so that the blocks move together will be $\dots \; N$.

Two blocks $(A)$ of $2\,kg$ and $(B)$ of $5\,kg$ rest one over the other on a smooth horizontal plane. The coefficient of static and dynamic friction between $(A)$ and $(B)$ is the same and equal to $0.60$. Find the maximum horizontal force that can be applied to $(B)$ such that both $(A)$ and $(B)$ do not have any relative motion. $(g = 10\,m/s^2)$

In the given arrangement,find the maximum value of $F$ for which there is no relative motion between the blocks.

The figure shows a two-block system. $A$ $4 \,kg$ block rests on a smooth horizontal surface,and the upper surface of the $4 \,kg$ block is rough. $A$ block of mass $2 \,kg$ is placed on its upper surface. Given $\mu_s = 0.8$ and $\mu_k = 0.6$ between the two blocks. The acceleration of the upper block with respect to the earth when the $4 \,kg$ mass is pulled by a force of $30 \,N$ is ......... $m/s^2$.