Restoring torque due to twist of torsion pendulum
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A torsion pendulum is a simple harmonic oscillator consisting of a disk suspended by a wire.
Rotating the disk through an angle in either direction introduces a restoring torque.

**Links:**

#. `Wikipedia, scalar equation <https://en.wikipedia.org/wiki/Torsion_spring#Torsion_coefficient>`__.

.. py:currentmodule:: symplyphysics.laws.dynamics.vector.restoring_torque_due_to_twist_of_torsion_pendulum

.. py:data:: torque

    Pseudovector of :attr:`~symplyphysics.symbols.classical_mechanics.torque` of the pendulum.

Symbol:
    :code:`tau`

Latex:
    :math:`{\vec \tau}`

Dimension:
    :code:`force*length`


.. py:data:: torsion_stiffness

    :attr:`~symplyphysics.symbols.classical_mechanics.torsion_stiffness` of the pendulum.

Symbol:
    :code:`kappa`

Latex:
    :math:`\kappa`

Dimension:
    :code:`force*length/angle`


.. py:data:: angular_displacement

    Pseudovector of angular displacement. See :attr:`~symplyphysics.symbols.classical_mechanics.angular_distance`.

Symbol:
    :code:`theta`

Latex:
    :math:`{\vec \theta}`

Dimension:
    :code:`angle`


.. py:data:: law

    :code:`tau = -kappa * theta`


    Latex:
        .. math::
            {\vec \tau} = - \kappa {\vec \theta}