The Difference Between Mass and Weight

steps What is the difference between mass and weight? I think it's something that a lot of people are confused about. They just think that anything that's big, like this car, has a lot of weight; it's very heavy, it's got a lot of mass, and people just basically think of these ideas as all the same.

But there's an important distinction between the terms mass and weight. Mass at first is the amount of matter in an object, whereas weight is a force. It's the gravitational attraction that the object feels towards, in this case, the Earth's center. So, I've got a little experiment today where I brought my car here and asked some people, "Why is it difficult to push my car?"

And my bet is the answer will be, "Because the car is heavy." (no duh) Because it's heavy. Because it's too heavy. (we get it, your car is heavy.) A big rock you would think would be heavy. It's too heavy. It's been lighter than I thought. It is because its weight. Weight is responsible.

What is weight? Weight is mass in gravity. What is this gravity thing? Gravity is what keeps ... talking indecisively your car is pulled towards the center of the earth, yes. But now when you push it, as in pushing your car, you are not pushing it up. Do you know what I mean? But it's still hard to push.

Yeah. So do you think weight is responsible for making it hard to push? But I'm not trying to lift the car; I'm just trying to push it. A big rock you would think would be heavy. Anything that is big, we think it would be heavy, but I'm not lifting it; I'm pushing, so it's also gravity. But this is my question, right? But I'm not trying to lift it.

No, that's true. But it's still hard to push. So why is that? Because, like, if I lift it, I understand you are saying it's heavy and it'd be really hard, but we're pushing it, actually getting it to go. So how does that work? The answer is because the car has inertia.

Inertia means that objects with mass have a tendency to resist changes in their motion. And I thought she had a great answer when I started, which was inertia. Can you tell us about that? What's inertia? It's just like once something stops, it doesn't really want to go unless something is going. It doesn't mind and would stop.

The idea that I'm trying to get is actually that these are actually two different things, right? One thing is that there's a force pulling a stand into the earth, and that's what we call weight, and that makes it impossible to lift. But there's something else, which is called inertia, and that means something is difficult to change its motion because it's got a lot of inertia, and that's why it's difficult to push, which is different than when it's difficult to lift.

Which is the weight force pulling it down towards here. Fair enough, but it's actually not as difficult to push. It's not that hard, yeah. I know it doesn't prove my point. (Subtitles by Jimena)