The terms mass and weight are often used interchangeably in everyday life, but they don’t mean the same thing. Surprise, surprise!

What’s the difference? To find out, you only have to look at a bag of Skittles. Let me explain.

A bag of Skittles has 56 pieces of candy, depending on the size of the bag. No matter where you go in the universe, that bag will have the same amount of Skittles. That’s mass!

Mass doesn’t change either. Your mass, your dog’s mass, anythings is determined by the amount of matter in the thing.

Your weight though will change. Why? Because your weight is a force.

To get what I mean, we first have to take a closer look at gravity. Gravity is often measured as an acceleration. On earth, that comes out to 9.8 meters per second squared.

Remember the force equation? Force=Mass x Acceleration

So, if we have a mass, and we have a rate of acceleration, we can multiply those two to get a force!

In this case, weight is going to be given in Newtons, which can then be converted into pounds.

The great thing is, just like how you can rearrange the force equation, you can rearrange this one. You can figure out how much you’d weigh on other planets simply by knowing your mass and that planet’s gravity, or you could calculate gravity with weight and mass!

Pretty cool, right?

Thinking of weight in this way actually helps us to better understand weightlessness, too. Objects in a free fall moving at the same acceleration as gravity are weightless. Astronauts on the International Space Station experience weightlessness because they are falling around the earth. Gravity at that height still has 90% of its strength.

Of course, as with all things, there’s more to the story.