$A$ wooden block of mass $M$ lies on a rough floor. Another wooden block of the same mass is hanging from the point $O$ through strings as shown in the figure. To achieve equilibrium,the coefficient of static friction between the block on the floor and the floor itself is:

$A$ horizontal force just sufficient to move a body of mass $4 \,kg$ lying on a rough horizontal surface is applied on it. The coefficients of static and kinetic friction are $0.8$ and $0.6$ respectively. If the force continues to act even after the body has started moving, the acceleration of the body is (take $g=10 \,ms^{-2}$). (in $\,ms^{-2}$)

$A$ force of $19.6\, N$ when applied parallel to the surface just moves a body of mass $10\, kg$ kept on a horizontal surface. If a $5\, kg$ mass is kept on the first mass,the force applied parallel to the surface to just move the combined body is........ $N.$

$A$ force $\vec{F}=\hat{i}+4 \hat{j} \, N$ acts on the block of mass $1 \, kg$ shown in the figure. The coefficient of friction between the block and the surface is $\mu = 0.3$. The force of friction acting on the block is (Take $g = 10 \, m/s^2$)

Which of the following is self-adjusting in nature?

$A$ force of $98 \, N$ is required to just start moving a body of mass $100 \, kg$ over ice. The coefficient of static friction is