Limiting Friction

Understanding Limiting Friction

• Limiting friction is defined as the maximum frictional force that needs to be overcome to initiate motion. It acts when a body is just about to move or slide across the surface of another body.
• It is directly proportional to the normal reaction between the two surfaces.

Factors Affecting Limiting Friction

• The material of the surfaces in contact, their smoothness or roughness, and the presence of any lubricant have significant effects on limiting friction.
• The normal force or the weight of the body also influences limiting friction due to its proportionality to the normal reaction.
• The coefficient of friction is another factor, a higher coefficient meaning a greater limiting friction, and vice versa.

Calculating Limiting Friction

• Limiting friction can be determined using the formula: F = μR where ‘F’ represents the limiting friction, ‘μ’ is the coefficient of static friction, and ‘R’ is the normal reaction.

Understanding Static and Dynamic Friction

• Before motion begins and when friction is at max, it is called static friction. If you attempt to move an object but the force applied is less than the maximum static friction, the object will not move.
• Once motion starts, the friction is known as kinetic friction. It is usually less than the maximum static friction (limiting friction).

Practical Implications

• Comprehension of limiting friction guides the design of tires, brakes, shoes, and all other components where friction helps in generating grip.
• Knowledge of limiting friction is essential for taking safety measures to prevent situations where a high frictional force might result in injury or damage.
• Machinery efficiency can be optimized by understanding and controlling limiting friction.