Mechanics (Statics) — Equilibrium of a body on a horizontal rough plane

About this lesson

This unit introduces the concept of friction in mechanics, distinguishing between smooth and rough surfaces. It explains that friction arises from microscopic irregularities on surfaces and is quantified by the coefficient of friction. The unit covers the properties of static friction, including limiting static friction, and introduces kinetic friction. It defines the resultant reaction as the combination of normal reaction and friction, and explains the angle of friction, establishing that the coefficient of friction equals the tangent of the angle of friction. The unit then applies these concepts to solve equilibrium problems for a body on a horizontal rough plane, considering forces applied at various angles. Worked examples include pushing a box, a body connected by a string over a pulley, and finding the coefficient of friction when multiple forces act. The unit also includes a theoretical proof using Lami's rule to find the minimum force needed to move a body. By the end, students should be able to define friction-related terms, calculate friction forces, determine coefficients, and solve equilibrium problems involving rough horizontal planes.