Gravity
...t one object is very massive... like a planet. The force of attraction between you and the planet Earth is a noticeable force! We call the force of attraction between you and the Earth, your weight. Weight is another name for the force of gravity pulling down on you or anything else. G is the universal gravitational constant. It is basically a conversion factor to adjust the number and units so they come out to the correct value. This is a universal constant so it is true everywhere. m1 is the mass of one of the objects. m2 is the mass of the other object. r is the radius of separation between the center of masses of each object. FG is the force of attraction between the two objects. Important Concepts The direction of the force is not given by this formula since there are actually two forces equal in size but opposite in direction. This formula calculates them both. The formula is an inverse square law for radius of separation (notice the r2 on the bottom of the equation). This means that if you double the separation you quarter the force, or if you cut the separation in half you quadruple the force of attraction. If you double a single mass, you double the force. If you cut one of the masses in half, you cut the force in half. But if you double both masses you would quadruple the force. Common Misconceptions "There is no gravity in space." FALSE If there were no gravity in space, the space shuttle would not be able to orbit the Earth, the moon would not orbit the Earth, and the Earth would not orbit the Sun. The reason we tend to...