import math


def orbital_speed(planet, planatary_radius, altitude):
    """
    Calculate the orbital speed of an object.

    v = R*sqrt(g/(R+h))

    >>> from math import *
    >>> round(orbital_speed(Constants.Earth, 600000, 70), 3)
    2425.552
    """
    total_altitude = planatary_radius + altitude
    speed = planatary_radius * \
        math.sqrt(planet.GRAVITY / total_altitude)
    return speed