Angle of friction and angle of repose

 Angle of Friction:

 

• Angle of Friction is defined as the angle between the horizontal plane and the slope of a material when it just begins to slide.
• The angle of friction depends on the type of material, its surface roughness, and the normal force acting on it.
• To measure the angle of friction, one can place a block of material on a flat surface and slowly increase the slope until the material just begins to slide. 
• The angle between the flat surface and the slope is the angle of friction.

---

Angle of Repose:

• Angle of Repose is defined as the maximum angle at which a material can be stacked without slipping or collapsing.
• The angle of repose depends on the shape, size, and texture of the particles making up the material.
• To measure the angle of repose, one can pile up the material in a cone shape and measure the angle between the horizontal plane and the surface of the cone.
• The angle between the horizontal plane and the surface of the cone is the angle of repose.