The coefficient of friction $\mu $ and the angle of friction $\lambda $ are related as

In the figure shown, a block of weight $10 \,N$ resting on a horizontal surface. The coefficient of static friction between the block and the surface ${\mu _s} = 0.4$. A force of $3.5\, N$ will keep the block in uniform motion, once it has been set in motion. A horizontal force of $3 \,N$ is applied to the block, then the block will

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 horizontal force of $10 \,N$ is necessary to just hold a block stationary against a wall. The coefficient of friction between the block and the wall is $0.2$. the weight of the block is ........ $N$

A mass of $4\; kg$ rests on a horizontal plane. The plane is gradually inclined until at an angle $\theta= 15^o$ with the horizontal, the mass just begins to slide. What is the coefficient of static friction between the block and the surface ?

A heavy uniform chain lies on a horizontal table-top. If the coefficient of friction between the chain and table surface is $0.25$, then the maximum fraction of length of the chain, that can hang over one edge of the table is ...... $\%$