What is the normal force on a body of mass $m$ placed on an inclined plane of angle $\theta$?

The horizontal acceleration that should be given to a smooth inclined plane of angle $\sin^{-1} (1/l)$ to keep an object stationary on the plane relative to the inclined plane is

$A$ perfectly smooth sphere $A$ of mass $2 \ kg$ is in contact with a rectangular block $B$ of mass $4 \ kg$ and a vertical wall as shown in the figure. All surfaces are smooth. Find the normal reaction exerted by the vertical wall on sphere $A$ (in $N$). Take $g = 10 \ m/s^2$.

$A$ block of mass $m$ is placed on a smooth fixed inclined plane with an angle of inclination of $37^{\circ}$. $A$ horizontal force $F$ is applied to keep the block at rest. Find the value of $F$.

$A$ truck of mass $30,000 \ kg$ moves up an inclined plane of slope $1$ in $100$ at a speed of $30 \ km/h$. The power of the truck is ................. $kW$ (given $g = 10 \ m/s^2$).

Three blocks of masses $2m$,$4m$,and $6m$ are placed as shown in the figure. If $\sin 37^{\circ}=\frac{3}{5}$ and $\sin 53^{\circ}=\frac{4}{5}$,the acceleration of the system is: