$A$ block of weight $1 \,N$ rests on an inclined plane of inclination $\theta$ with the horizontal. The coefficient of friction is $\mu$. The minimum force that has to be applied parallel to the inclined plane to make the body just move up the plane is

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

$A$ block of mass $5 \ kg$ is moving on an inclined plane which makes an angle of $30^{\circ}$ with the horizontal. The coefficient of friction between the block and the inclined plane surface is $\frac{\sqrt{3}}{2}$. The force to be applied on the block so that the block will move down without acceleration is . . . . . . $N$.

An inclined plane is bent in such a way that the vertical cross-section is given by $y = \frac{x^2}{4}$,where $y$ is in the vertical direction and $x$ is in the horizontal direction. If the upper surface of this curved plane is rough with a coefficient of friction $\mu = 0.5$,the maximum height in $cm$ at which a stationary block will not slip downward is............$cm$.

Two blocks $A$ and $B$ of equal mass are initially in contact when released from rest on an inclined plane. The coefficients of friction between the inclined plane and blocks $A$ and $B$ are $\mu_1$ and $\mu_2$ respectively.

$A$ body takes $n$ times as much time to slide down a $45^{\circ}$ rough incline as it takes to slide down a smooth $45^{\circ}$ incline. The coefficient of friction between the body and the incline will be