Mass & Weights

In common usage, the mass of a body is often referred to as its weight, although they are actually different concepts and quantities. In a scientific context, mass is the amount of "matter" in an object (although "matter" is hard to define), while weight is the force that gravity exerts on an object. In other words, an object of mass 1.0 kg on the surface of the Earth would weigh about 9.81 newtons, or its mass multiplied by the strength of the gravitational field. On Mars, where gravity is weaker, an object weighs less; And its weight increases on Saturn, where gravity is stronger, and space is very small and far from the source of gravity; But it still has the same mass.