What is Angle of Repose (α)?

Angle of Repose (α) #8211; The minimum angle of inclination (α) of a plane with the horizontal, such that a body placed on the plane just begins to slide down the inclined plane is known as angle of repose or angle of sliding. From figure, we have µ mg sinα = F = force of limiting friction mg cosα = R = Force of normal friction ⇒ tanα = F/R⇒ [α = tan_-1(µ)] or α = θ i.e. Angle of repose = Angle of friction