Mass explanation: I’ve always been told that mass was not the same as weight, and that grams are the metric unit of mass. But grams are a measurement of weight, so am I stupid, was it was explained to me wrong, or is science just not make sense?

Question

Mass explanation: I’ve always been told that mass was not the same as weight, and that grams are the metric unit of mass. But grams are a measurement of weight, so am I stupid, was it was explained to me wrong, or is science just not make sense?

In: 140

Answer 1

So your question is about words, as much as it is about science. In this case, it’s about two things that mean the same thing in one particular case, but they are very different things.

Mass is an amount of ‘stuff’.

Weight is the *force* that ‘stuff’ does to something else.

I have a mass of 100 kilograms. When I stand on a scale at home, I put 220 pounds of force on that scale. If I’m in space, I have a mass of 100 kilograms. But I step on the scale, and I am ‘weightless’.

If I step on a tree branch, then I am using 100 kg, in order to put 220 pounds of force on the tree branch. But I can also take a hammer that weighs 2 kg, and swing it really hard, and put 220 pounds of force on that tree branch.