Cylindrical Coordinate System Article Index for
Cylindrical
Website Links For
Coordinate
 

Information About

Cylindrical Coordinate System




The cylindrical coordinate system is a three-dimensional Coordinate System which essentially extends Circular Polar Coordinates by adding a third coordinate (usually denoted h) which measures the height of a point above the plane.

A point P is given as (r, heta, h). In terms of the Cartesian Coordinate System :
  • r is the distance from O to P', the orthogonal projection of the point P onto the XY plane. This is the same as the distance of P to the z-axis.

  • heta is the angle between the positive x-axis and the line OP', measured counterclockwise.

  • h is the same as z.

  • Thus, the conversion function f from cylindrical coordinates to Cartesian coordinates is f(x,y,z)=(r\cos heta,r\sin heta,h).


For use in physical sciences and technology, the recommended international standard notation is ''ρ'', ''φ'', ''z'' ( ISO 31-11 ).

Some mathematicians indeed use (r, heta, z).

Cylindrical coordinates are useful in analyzing surfaces that are symmetrical about an axis, with the z-axis chosen as the axis of symmetry. For example, the infinitely long circular cylinder that has the Cartesian equation ''x''2 + ''y''2 = ''c''2 has the very simple equation ''r'' = ''c'' in cylindrical coordinates. Hence the name "cylindrical" coordinates.


LINE AND VOLUME ELEMENTS

See Multiple Integral for details of volume integration in cylindrical coordinates, and Del In Cylindrical And Spherical Coordinates for Vector Calculus formula.

In many problems involving cylindrical polar coordinates, it is useful to know the line and volume elements; these are used in integration to solve problems involving paths and volumes.

The Line Element is dl = dr\,\mathbf{\hat r} + r\,d heta\,\boldsymbol{\hat heta} + dz\,\mathbf{\hat z}.

The volume element is dV = r\,dr\,d heta\,dz.

The Gradient is
abla = \mathbf{\hat r} rac{\partial}{\partial r} + \boldsymbol{\hat heta} rac{1}{r} rac{\partial}{\partial heta} + \mathbf{\hat z} rac{\partial}{\partial z}.


SEE ALSO