Block $A$ of mass $30\, kg$ . is resting on a frictionless floor. Another block $B$ of mass $5\, kg$  is resting on it as shown in the figure. The coefficient of static friction between the blocks is $0.4$ while kinetic friction is $0.3$. If a horizontal force of $175\, N$ is applied to block $B$ , then the acceleration of the block $A$ will be …….. $m/s^2$  $(g = 10\, m/s^2 )$

Imagine $a$ situation in which the horizontal surface of block $M_0$ is smooth and its vertical surface is rough with $a$ coefficient of friction $\mu$ In above problem, choose the correct value $(s)$ of F which the blocks $M$ and $m$ remain stationary with respect to $M_0$

$A$ block of mass $M$ is placed on $a$ horizontal surface and it is tied with an inextensible string to $a$ block of mass, as shown in figure. A block of mass $m_0$ is also placed on $M$ If friction force exists between the block $M$ and the block $m_0$ and not between the block $M$ and the horizontal surface, then the minimum value of $\mu$ for which the block m remains stationary 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 coefficient of friction between $A$ and $B$ is $0.4$, the maximum horizontal force which can make them without separation is …….. $N$