"""
My physics.
"""

import math

def free_fall(time, initial_speed=0, gravity=9.82):
    """
    Calculates the speed of an object falling through empty space.
    """
    return initial_speed + gravity * time

def kinetic_energy(mass, velocity):
    """
    Calculates the kinetic energy from the mass and velocity of an object.
    """
    return 0.5 * mass * math.pow(velocity, 2)

def height(energy, mass, gravity=9.82):
    """
    Calculates the height from the kinetic energy of an object and the gravity affecting it.
    """
    return energy / (mass * gravity)

def gravitational_pull(mass1, mass2, distance):
    """
    Calculates the gravitational pull between two objects given the distance between them.
    """    
    G = 6.674 * math.pow(10, -11)
    return G * mass1 * mass2 / math.pow(distance, 2)