def spring_and_friction(mass, damping_ratio, natural_freq):
    """
    Compute spring rate and friction coefficient from a given damping ratio and natural frequency
    :param mass: Mass, valid range [0, np.inf)
    :type mass: float
    :param damping_ratio: Damping ratio of components, valid range [0, np.inf),
                          1 is critical damping, <1 is underdamped, >1 is overdamped
    :type damping_ratio: float
    :param natural_freq: Natural frequency of components, valid range [0, np.inf)
    :type natural_freq: float
    :return: Spring rate and natural frequency
    :rtype: float, float
    """
    spring = mass*(natural_freq**2)
    friction = 2*mass*damping_ratio*natural_freq
    return spring, friction