Physics
=======

Write the Phyton functions to solve the following physics
problems:

#. Write the function :py:func:`amps`, that from a given electric
   potential difference value expressed in volts and a given
   resistance value expressed in ohms of an electric circuit, returns
   the electric current intensity in accordance to Ohm's law.
   
   Save the function into the file named :file:`physics1.py`. The
   function must pass the following doctest:

   .. literalinclude:: physics1.txt
      :language: python3
      :lines: 3-8

   .. note::

      You can download the file with tests :download:`physics1.txt <physics1.txt>`

      
#. Write the function :py:func:`velocity` that, given a time in
   minutes and a distance in kilometers, corresponding to a uniform
   lineal motion of a body travel, returns its velocity in m/s.

   Save the function into the file named :file:`physics2.py`. The
   function must pass the following doctest:

   .. literalinclude:: physics2.txt
      :language: python3
      :lines: 3-8

   .. note::

      You can download the file with tests :download:`physics2.txt <physics2.txt>`

      
#. Write function :py:func:`ualm` that given the acceleration (in
   :math:`\mathrm{m/s}^2`), the starting velocity
   (in :math:`\mathrm{m/s}`), the starting position, in meters, and a
   time in minutes, corresponding to an uniformly accelerated linear
   motion of a body travel, returns the final position of this body in
   meters.

   Save the function into the file named :file:`physics3.py`. The function must pass 
   the following doctest:

   .. literalinclude:: physics3.txt
      :language: python3
      :lines: 3-8

   .. note::

      You can download the file with tests :download:`physics3.txt <physics3.txt>`

      
#. An automobile is at the origin and travels in a uniform linear
   motion with a velocity ``v1`` expressed in km/h. Another car that
   is at a distance of ``x`` meters forward from the previous one
   starts to move ``t`` seconds after the first car and in the same
   direction at a constant velocity ``v2`` (in km/h).  Write the
   function :py:func:`car` that given ``v1``, ``v2``, ``x`` and ``t``
   returns the time (in seconds) that the first car needs to catch up
   with the second one. We will assume that velocity ``v2`` in
   inferior than ``v1`` and that the first car will catch up with the
   second one after the second one starts moving.
   
   Save the function into the file named :file:`physics4.py`. The
   function must pass the following doctest:

   .. literalinclude:: physics4.txt
      :language: python3
      :lines: 3-8

   .. note::

      You can download the file with tests :download:`physics4.txt <physics4.txt>`

.. rubric:: Solution

A solution of these functions is provided in the
:download:`physics1.py<solutions/physics1.py>`,
:download:`physics2.py<solutions/physics2.py>`,
:download:`physics3.py<solutions/physics3.py>`,
:download:`physics4.py<solutions/physics4.py>`