mass vs weight

Question

Conceptually I understand that mass is a measure of the amount of stuff present in an object, while weight is a measure of the force of gravity applied to that object. An object of a given mass will have a bigger weight on Earth than on the moon because Earth’s gravity is stronger. But… mass is determined by weighing an object on a scale. And there is a simple mathematical conversion between grams (mass) and pounds (weight), implying that they’re just different units for the same concept. So what gives? (Also this is a question that applies to so many fields, I had no idea which flair to apply.)

In: 53

Answer 1

The difference of these two concepts became apparent to science in the 17th century with the Newton laws. Although he knew the conceptual difference, he used the same word as weight for mass too, as there were no terms coined yet.

In the everyday life it’s a very hard to grasp difference, because you cannot just grab your bathroom scale and check your weight on the moon, and in general, things that have more material naturally have more weight with some weird exception.

Because the imperial system was invented before the distinction was made (and anyways it’s fir everyday use), US people don’t even have different units for weight and mass so they take kilograms from the metric system. Which makes it feel not integral part of the system. (Also in the US there’s this thing called mass-pound (lbm), to cause some more confusion.)

In Europe the bathroom scales and in general the weights of stuff are given in grams or kilograms so basically in mass units. I have my cooking recipes in kilograms. Weight unit in the metric system is called newton but it’s not used in the everyday life. (It’s newton because weight is defined as the downward force an object exerts on the support, and force unit in metric system is newton.)

But in fact European scales cheat because although they tell the results in kilograms, they do not measure mass. They measure in fact the change of electric current due to deformation of a thin wire inside, which is proportional to force. So they measure force but give the result in mass.