空間における線積分

A line integral in space accumulates values along a three-dimensional path, such as a thin coiled spring represented by the trajectory curve C.

The path is defined by a position vector r, which represents the x, y, and z coordinates in terms of a single parameter, usually time or angle.

As the parameter changes, the vector traces a smooth and continuous curve through space, defining the trajectory.

When the function does not have a direction, like density, a scalar line integral is applied. In this case, the function is integrated with respect to arc length to determine the total mass of a spring distributed along a curve.

In contrast, a vector line integral is used when the path interacts with a vector field F, such as a gravitational force. Here, the integral only accounts for the portion of the force acting in the direction of motion.

For instance, when a particle travels along a helical path within a vector field, the work done is computed by summing the tangential component of the field at every point.

These line integrals are used to calculate the accumulation of a specific quantity along various spatial paths.