Equations of Motion: Rectangular Coordinates and Cylindrical Coordinates

Understanding the motion of particles is a fundamental aspect of classical mechanics, and the choice of the coordinate system plays a pivotal role in unraveling the complexities of their dynamics.

When a particle moves relative to an inertial frame, the equations of motion can be expressed using rectangular components. If the motion is confined to the x-y plane, the equations having the x and y coordinates only can be used to simplify the mathematical representation.

However, when particles follow a curved path, the cylindrical coordinate system becomes indispensable. Introducing radial, azimuthal, and axial components aligned with their respective unit vector directions, this system adds a vertical dimension to the analysis, essential for capturing the nuances of three-dimensional motion. Within this framework, the force along each component determines the acceleration along its corresponding direction. The radial acceleration, for instance, represents the difference between the particle's acceleration along the radial direction and the product of its radius and angular velocity. Conversely, the azimuthal acceleration is a composite of the product of radius and angular acceleration coupled with the product of radial and angular velocity. This equation explains the change in the particle's position along its curved trajectory, providing valuable insights into the rotational aspects of its motion. The axial acceleration reflects the changes in the particle's speed along the vertical axis of the cylindrical system, offering an understanding of the particle's dynamics in space.

Whether leveraging the simplicity of rectangular coordinates or embracing the additional dimensions of cylindrical coordinates, each approach enhances the understanding of how particles move and interact with their surroundings.