1. Is 'surface gravity' the same as 'gravitational field strength'? 2. It seems to me that the 'g' in the formula w = mg sometimes refers to acceleration due to gravity (measured in m/s^2) and sometimes refers to something else that I've not quite grasped yet (measured in N/kg) ; what is the something else? And do the values of each always match exactly, ie, acceleration due to gravity near the surface of the Earth is 9.8 m / s ^2 and the magnitude of the 'something else' is 9.8 N/kg (likewise for on or near the Moon; 1.6 m/s^2 and 1.6 N/kg).