Cross section of interaction in model of hard spheres
=====================================================

The model used in this law assumes atoms to be hard spheres, in which case the cross
section of the interaction between the atoms is proportional to the square of the
distance of greatest convergence between the atoms.

**Conditions:**

#. All atoms are spheres of equal radius.

**Links:**

#. `Wikipedia, second formula <https://en.wikipedia.org/wiki/Cross_section_(physics)#Collision_among_gas_particles>`__.

.. py:currentmodule:: symplyphysics.laws.chemistry.cross_section_of_interaction_in_model_of_quasirigid_spheres

.. py:data:: cross_section

    :attr:`~symplyphysics.symbols.chemistry.cross_section` of interaction of particles.

Symbol:
    :code:`sigma`

Latex:
    :math:`\sigma`

Dimension:
    :code:`area`


.. py:data:: distance_of_convergence

    :attr:`~symplyphysics.symbols.classical_mechanics.euclidean_distance` of greatest convergence of two colliding particles. In
    other words, this is the diameter of spheres which approximate the atoms.

Symbol:
    :code:`d`

Latex:
    :math:`d`

Dimension:
    :code:`length`


.. py:data:: law

    :code:`sigma = pi * d^2`


    Latex:
        .. math::
            \sigma = \pi d^{2}