Mass is the amount of matter in an object. When you record mass the unit you use is grams. A medium sized leaf is about 1 gram, a potato chip 2 grams. A larger unit of mass is a kilogram. A kilogram is about the mass of a medium sized textbook. You need a balance to find mass. There are many kinds of balances. The gram is the unit used to measure mass. Mass is a measure …showed first 75 words of 683 total…

…showed last 75 words of 683 total…from the earth, which may be only 200 kilometers or so. They are weightless because they are in free fall, as you would be if you fell off a cliff. They don't fall straight down, however, because they are traveling forward at about 30 times the speed of sound (mach 30), and keep missing the earth! The sailors who refused to travel with Columbus were right. You can fall off the earth (if you are moving fast enough).