The maximum force of friction is called:

What is the maximum acceleration of a train such that a $50 \ kg$ box lying on its floor remains stationary (in $m \ s^{-2}$)? (Given: Coefficient of static friction between the box and the train's floor is $0.3$ and $g = 10 \ m \ s^{-2}$)

The coefficient of friction between an object and a surface,if we need to move an object of weight $150 \ N$ on a horizontal surface with a force of $75 \ N$,is

$A$ body of mass $4\, kg$ is at rest on a horizontal table. The coefficient of friction between the body and the table is $0.2$. $A$ horizontal force of $6\, N$ is applied on the body. The acceleration of the body is .......... $m/s^2$.

$A$ block of mass $M$ is placed on a horizontal surface and it is tied with an inextensible string to a block of mass $m$,as shown in the figure. $A$ block of mass $m_0$ is also placed on $M$. If $\mu$ is the coefficient of friction between the block $M$ and the horizontal surface,then the minimum value of $m_0$ required to keep the block $m$ stationary is

Two masses $A$ and $B$ of $10\, kg$ and $5\, kg$ respectively are connected with a string passing over a frictionless pulley fixed at the corner of a table as shown. The coefficient of static friction of $A$ with the table is $0.2$. The minimum mass of $C$ that may be placed on $A$ to prevent it from moving is ........ $kg$.