An object's gravitational force is that object's strength in attracting other objects. Gravitational force depends on mass and distance. Objects with a larger mass have a greater gravitational force. Stars or planets, for example, exert a stronger gravitational force than a ping-pong ball or a marble.
Weight is a measure of the gravitational force exerted on an object. We usually measure the weight of an object on the surface of the Earth. But you could take your weight anywhere, and it would vary depending on what you were near. Your weight would be much greater on the sun because of its huge mass, but much less if you were on the moon or floating in outer space. In America, we usually measure weight in pounds. In science, we measure weight in newtons, a unit named for Sir Isaac Newton who made several discoveries about gravity. To make measuring easier, scientists decided that one newton would be very close to 100 grams of mass on Earth, about the weight of a bar of soap. This means that if you know the weight of an object on Earth, you can tell its mass as well: 500 grams of mass would equal 5 newtons on Earth. Likewise, 2 newtons would equal 200 grams on Earth.
When you measure a person’s weight, you are measuring the
A
gravitational force of the Sun on the Earth.
B
gravitational force acting on that person.
C
volume of that person.
D
density of that person.