Answer :
Because mass shows how much is in an object, weight is just how much the object weighs.
-- Mass is actually a property of the object or the blob of matter.
It doesn't change as the piece of matter moves around.
-- Weight is not a property of the blob of matter. It depends on
what else is around, and it changes as the matter moves around
from one place to another.
Example:
You might have a bottle of water. Its mass could be 1 kilogram.
The mass never changes. It's a property of the matter in the bottle.
But when you take it to the Moon, it weighs about 5.8 ounces.
When you take it to the Earth, it weighs about 2.205 pounds.
When you take it to Mars, it weighs about 13.3 ounces.
When you take it to Jupiter, it weights about 5.6 pounds.
If you try and put it on scale and weigh it while you're in the space ship
coasting from one place to another, it weighs nothing at all and it floats
off of the scale.
Even though the mass never changes !
