area of contact

shape of surfaces

strength of surfaces

nature of surface

along the plane

horizontally

vertically

at an angle equal to the angle of friction to the inclined plane.

coefficient of friction

angle of friction

angle of repose

sliding friction

the tangent of the angle of friction is equal to coefficient of friction

the angle of repose is equal to angle of friction

the tangent of the angle of repose is equal to coefficient of friction

the sine of the angle of repose is equal to coefficient to friction

towards the wall at its upper end

away from the wall at its upper end

upwards at its upper end

downwards at its upper end