Mass and weight. One kilogram mass being weighed on a newtonmeter. Mass is a measure of the amount of matter an object contains, and is constant in any situation. Weight, on the other hand, is a measure of the effect of gravity on mass, and thus varies as the gravitational field does. The newtonmeter is reading just less than 10 newtons as Earth's gravitational field produces a acceleration of just less that 10 metres per second per second. On the Moon, whose gravity is one sixth of Earth's, one kilogram would weigh 1.7 newtons.