Angular position is arc length over radius
==========================================

To describe the rotation of a rigid body about a fixed rotational axis, a reference line is
assumed to be fixed in the body, perpendicular to that axis and rotating with the body. The angular
position of this is measured relative to a fixed direction and is expressed as a ratio of the arc
length of a circular path and its radius (distance to the axis).

**Links:**

#. `Wikipedia, similar concept <https://en.wikipedia.org/wiki/Central_angle#Formulas>`__.

#. `openstax, table 6.2, first line <https://openstax.org/books/physics/pages/6-3-rotational-motion>`__.

.. py:currentmodule:: symplyphysics.laws.kinematics.angular_position_is_arc_length_over_radius

.. py:data:: angular_position

    :attr:`~symplyphysics.symbols.classical_mechanics.angular_distance` of the body.

Symbol:
    :code:`theta`

Latex:
    :math:`\theta`

Dimension:
    :code:`angle`


.. py:data:: arc_length

    :attr:`~symplyphysics.symbols.classical_mechanics.arc_length` of the curve traced by the body's movement.

Symbol:
    :code:`s`

Latex:
    :math:`s`

Dimension:
    :code:`length`


.. py:data:: distance_to_axis

    :attr:`~symplyphysics.symbols.classical_mechanics.distance_to_axis` of rotation, or radius of rotation.

Symbol:
    :code:`r`

Latex:
    :math:`r`

Dimension:
    :code:`length`


.. py:data:: law

    :code:`theta = s / r`


    Latex:
        .. math::
            \theta = \frac{s}{r}