What is the Difference Between Sliding and Rolling friction?

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The main difference between sliding and rolling friction lies in the way the objects interact with the surfaces they are in contact with. Here are the key differences between the two types of friction:

  • Occurrence: Sliding friction occurs when two surfaces are rubbed against each other, while rolling friction takes place when an object rolls on a surface.
  • Motion: A rolling body executes both translational and rotational motion, whereas a sliding body only executes translational motion.
  • Cause: Sliding friction is caused by the interlocking between microscopic surfaces, while rolling friction is due to the deformation of surfaces.
  • Contact: In rolling friction, only a point on the surface remains in contact with the object, while in sliding friction, a finite area of the surface remains in contact with the object.
  • Dependence: Rolling friction depends on the geometry of the object, its weight, and the texture of the surface in contact. Sliding friction depends on the weight of the object and the texture of the surface in contact with it.
  • Formula: Rolling friction is given by the expression $$fr = \mur N$$, where $$fr$$ is the rolling friction force, $$\mur$$ is the coefficient of rolling friction, and $$N$$ is the normal force. In contrast, sliding friction is given by the expression $$fk = \muk N$$, where $$fk$$ is the sliding friction force, $$\muk$$ is the coefficient of sliding friction, and $$N$$ is the normal force.
  • Strength: Rolling friction is generally weaker than sliding friction or static friction, which is why most forms of ground transportation use wheels to reduce friction.

Comparative Table: Sliding vs Rolling friction

Here is a table comparing sliding friction and rolling friction:

Property Sliding Friction Rolling Friction
Definition The force of friction generated when an object slides over the surface of another object. The force of friction generated when an object rolls over the surface of another object.
Occurrence Takes place when two surfaces are rubbed against each other. Takes place when an object rolls on the surface.
Causes Surface roughness, adhesive forces between the two surfaces. Deformation of surfaces, rolling resistance.
Coefficient Coefficient of sliding friction, which represents the frictional characteristics of the surfaces. Coefficient of rolling friction, which is determined by the quality of the sliding body, surface, load, diameter of the rolling object, and surface area of the body.
Energy Loss Higher energy loss due to resistance. Lower energy loss, more energy-efficient.
Applications Used in engineering and design processes to choose the best materials and surface treatments. Used to study the motion of objects with less resistance, such as wheels rolling on the ground or a ball rolling on a table.

In summary, sliding friction occurs when two surfaces are rubbed against each other, generating resistance due to surface roughness and adhesive forces. Rolling friction, on the other hand, takes place when an object rolls over a surface, offering a smoother motion with lower friction and energy loss.