Re: May I join?
Posted by Dale on Feb 28, 2002 at 10:21
Re: Nicely articulated (bobbapink)
Yes, you can measure the attraction of A and B toward C without observing C. This does tell you the mass of C. This is done all the time. A popular finding is the need for "dark matter" in the universe to explain the observed galactic motions.
But you can also determine if A and B are attracting each other or not. Let’s try to do a word picture for Natalie. Assume A and B are stationary at an equal distance from a stationary C. Let go of everything with A and B attracted to C but not to each other. A and B will each travel on a line from their center to the center of C. As they travel toward C the distance between A and B will decrease “simulating” an attraction. The paths A and B trace will be straight. They will touch each other as they touch the center of C. Now add an attraction between A and B. The paths will no longer be straight. They will curve toward each other. A and B will collide before they reach C which they would never do if there is no attraction between them.