def Velocity(velocity, acceleration, i):
    """Defines the velocity at timestep i.
    Args:
        velocity (float): Initial velocity = 0. Recursively updates the velocity_new
        acceleration (float): From rocket.Acceleration(), Instantaneous acceleration.
        i (int): Iterator used for Euler's Method
    Returns:
        velocity_new (float): Updated velocity. Will replace velocity for next iteration
    """

    # F = m*a
    TIME_STEP = .1

    velocity_new = velocity + acceleration * TIME_STEP
    #v_x = velocity * np.sin(theta)
    #    v_y = velocity * np.cos(theta)

    # acceleration = (thrust - drag) / mass_ship
    return velocity_new