Mass v. weight

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Home : 2004 : January : 12

Mass v. weight
By Doni

I'm teaching this to my 5th graders right now. This is what I told them, and they seemed to get it.
I explained to them that mass is the amount of matter in an object. I told them to think of matter as stuff that an
object is made of. I explained that the matter of an object never changes no matter where that object goes. I then explained that weight is the pull of gravity on an object - the greater the mass, the greater the pull; therefore, the greater the weight. I explained that gravity varies depending on where you are. The moon's gravity is 1/6 the earth's gravity, so one would weight one sixth

their earth weight on the moon, but one's mass would be the same. I used a kid in my class as an example. She weighs 60 pounds and wears a size 10 slim jeans. On the moon she would weigh 10 pounds, but she would still wear a size 10 slim jean, because her mass would not change. There would still the same amount of matter inside her, it would just weigh less because there isn't as much gravity. Even though she would only weigh 10 pounds, she would look exactly the same.

They seemed to get this. I then explained how the planets have different masses and so they have different gravities. The moon's gravity is 1/6th the earth's because its mass is so much less. Jupiter on the other hand would have a far greater gravitational pull than the earths, since it's mass is so much greater. This would mean a my skinny minnie would weigh about 180 pounds on Jupiter, but she'd still wear a 10 slim jeans.