Differensialt

Differensialt, or differential, refers to a small or infinitesimal change in a quantity and to the mathematical framework that studies such changes. The term is used in various fields, including calculus, physics, engineering, and economics, and is etymologically linked to the French différentiel.

In calculus, a differential dy represents the linear approximation of the change in y caused by a small change dx in x: dy = (dy/dx) dx. For a function of several variables, the total differential summarizes changes across all variables: dz = sum_i (∂f/∂xi) dxi. Differentials provide a convenient notation for expressing rates of change and for performing linear approximations.

Differential equations are equations that involve derivatives of an unknown function. Ordinary differential equations (ODEs) involve derivatives with respect to a single variable, while partial differential equations (PDEs) involve derivatives with respect to multiple variables. They model a wide range of phenomena, from mechanical motion to population growth and electrical circuits, and are solved analytically in simple cases or numerically in more complex ones.

Applications of the differential concept span science and engineering. In physics, differentials underpin work, energy, and motion analyses. In engineering and economics, they support modeling of dynamic systems, optimization, and sensitivity analyses. The language of differentials also underpins numerical methods, providing a foundation for algorithms that approximate solutions to differential equations and for error estimation in simulations.

Mechanical differentials, a specific engineering use, are gear arrangements in vehicles that split torque between wheels while allowing different wheel speeds during turning. They enable smooth cornering and reduce tire wear. Types include open differentials and limited-slip differentials, each balancing torque distribution and traction in varying conditions.