The second type of vis-viva equation is used to calculate the velocity of an object in an elliptical orbit around a massive body. This equation states that the velocity is equal to the square root of the gravitational constant times the mass of the planet or moon divided by the semi-major axis of the ellipse, multiplied by the difference between two values: one minus the eccentricity of the orbit, and one plus the radius of the planet or moon divided by the semi-major axis of the ellipse.