In this edition of Cosmically Curious, Patrick McNameeKing chats with astronomer Nicole Gugliucci of Saint Anselm College about a familiar source of scientific confusion: Mass and weight aren’t the same thing.
From Earth to the Moon, Gugliucci explains how gravity changes your weight while your mass stays the same — and why that could mean a lot more chocolate.
Transcript:
Patrick McNameeKing: Nicole, sometimes on this program, we talk about the mass of giant things in space. I'm talking about planets and stars and all that. And I've always thought of mass as the same thing as weight.
But I recently learned this is incorrect. So what's the difference between mass and weight?
Nicole Gugliucci: Mass is basically how much stuff a thing is made of. Weight is how much force that thing puts on, say like a planet or a world that it's standing on.
So my mass doesn't change whether I'm standing on the earth or standing on the moon, right?
I am the same amount of stuff — assuming, you know I'm in a spacesuit and safe — but my weight would change.
The amount of force I put on a scale standing on earth, gravity is a lot more than the amount of force I put on a scale standing on the moon.
Patrick McNameeKing: That makes sense. Gravity on the moon is one sixth of what it is on earth. I get it.
Nicole Gugliucci: And I like to give students a question to think about. I say, if you were going to buy a pound of really nice special chocolate, would you rather get a pound of chocolate on the moon or a pound of chocolate on the earth?
And they have to sit there and think about how weight relates to mass. And if you want more chocolate, you're gonna get the pound on the moon because it's going to be six times as much chocolate as you would get on earth.
Patrick McNameeKing: That's a great way to think about it.
If you have questions about the night sky or maybe where to find the best chocolate on the moon, send us an email at cosmic@nhpr.org.
