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

Assume the universe existed of only balls (the kind that you play sports with, not the ones that all men normally have).

Assume all balls were exactly the same size. Since the universe is made out of balls, you can assume the material the balls are made of “themselves”, so it’s not like one ball is any different than another in terms of material or density and such.

Anyway, mass is basically a count of how many balls something is made of. If I make a statue out of balls, regardless of where I am (underwater, on Mars, on earth, on the moon), the statue is made up of the same number of balls.

Weight is how hard will the statue crush me? In space, it’ll weigh nothing. Because it can’t crush me at all. I guess I’m missing a technicality – weight is how much can something crush me while it’s not moving, but is being attracted towards something when not moving. This is needed to be specified, because if I jump, I’m technically a negative weight by this logic, and when I’m falling back down from the jump, I actually end up weighing more (which is why you might not break a table if you stand on it, but likely will if you jump).

The reason we can swap weight and mass often (“2.2 lbs = 1 kg”) is because how hard you can crush something when at rest is the same all over earth for the most part. You get a little lighter if you’re on a mountain, but not enough to be noticable.

But yeah, if you’re not on earth anymore, 2.2 lbs is no longer 1 kg. You’ll still be whatever kg you were, but you won’t be the same lbs. This is because 1 kg will weigh less on the moon, and so will you. But if you were 100 kg on earth, then you’ll be 100 kg on a tiny planet. But that 100 kg may suddenly weigh 30 lbs. And in that case, you’ll be 30 lbs (but still 100 kg).

The 2.2 is missing a “*on earth” disclaimer.

So back to balls. Your statue is still the same number of balls (kg). But the weight (how hard the balls are pressing down) will change depending on how large the planet/object you’re standing on is.