A block is stationary on a rough inclined plane. How many forces are acting on the block?

A coin placed on a rotating table just slips when it is placed at a distance of $1\,cm$ from the center. If the angular velocity of the table in halved, it will just slip when placed at a distance of from the centre $............\,cm$

Abody is placed on a rough inclined plane of inclination $\theta$ .As the angle $\theta$ is increased from $0^o$ to $90^o$ the contact force between the block and the plane

Block $B$ of mass $100 kg$ rests on a rough surface of friction coefficient $\mu = 1/3$. $A$ rope is tied to block $B$ as shown in figure. The maximum acceleration with which boy $A$ of $25 kg$ can climbs on rope without making block move is:

A block of mass $5\, kg$ is kept on a rough horizontal floor. It is given a velocity $33\, m/s$ towards right. A force of $20\sqrt {2\,} \,N$ continuously acts on the block as shown in the figure. If the coefficient of friction between block and floor is $0.5$ the velocity of block after $3\, seconds$ is ........ $m/s$  ($g = 10\, m/s^2$)

A block of mass $1\,kg$ lies on a horizontal surface in a truck. The coefficient of static friction between the block and the surface is $0.6$ . If the acceleration of the truck is $5\,m\,s^{-2}$ . The frictional force acting on the block is ........ $N$