If for an inclined plane coefficient of static friction is ${\mu _s} = \frac{3}{4}$, then for the inclined plane angle of repose will be ........ $^o$

Static friction between two surfaces

A marble block of mass $2\, kg$ lying on ice when given a velocity of $6\, m/s$ is stopped by friction in $10s$. Then the coefficient of friction is-

Meena applies the front brakes, while riding on her bicycle along a flat road. The force that slows her bicycle is provided by the

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 $20\, kg$ block is initially at rest on a rough horizontal surface. A horizontal force of $75 \,N$ is required to set the block in motion. After it is in motion, a horizontal force of $60\, N$ is required to keep the block moving with constant speed. The coefficient of static friction is