# superposition

Suppose I take a 1 kg ball and hold it near the surface of the Earth. What would be the gravitational force the Earth exerts on this ball?
And I could say "g" is:
The magnitude of this force would then be 9.8 Newtons. And, if I replaced the ball with a 10 kg ball, the force would be 98 Newtons. What does this have to do with the electric field? Well, you are probably already familiar with this idea of the gravitational force. Guess what? "g" is the gravitational field. Basically, it is the force per unit mass due to the Earth. This is only approximately constant. If I get very far…