Pushing gravity mechanics

Does the gravity constant change any at all at zero kelvin? Gravity is not effected by 1,000k or 2,000k why should 1k make any difference?

For those who are interested. Thousands of experiments have been done dropping all manner of materials with rotation, without rotation, with temperature increase and so on. While some interesting data exists the results have not been definitive in assailing the basic notion that all bodies fall at the same rate. If ANY of these effects are real they are so small that you can in practical effect ignore them. As for the gravitational constant changing with temperature there is current doubt about the constancy of it period. Recent measurements have not honed in on the same value and some individuals are proposing things like it being related to latitude or such. Still a lot of experimental work to be done.

<BLOCKQUOTE id=quote><font size=2 face="Verdana, Arial, Helvetica" id=quote>quote:<hr height=1 noshade id=quote>[Jim]
The equal and opposite fall of the Earth is missing in the posts above The Earth is accelerated into the greater mass at a higher rate and so it should reach the greater mass first-right?<hr height=1 noshade id=quote></BLOCKQUOTE id=quote></font id=quote><font face="Verdana, Arial, Helvetica" size=2 id=quote>
Yes, of course.

If you build a drop tower on each of the smaller masses, carry the Earth to the top of each tower and drop it, it will accelerate faster on the larger mass than on the smaller mass.

The difference in the acceleration of the Earth in each case is proportional to the ratio of the smaller masses. And independent of the Earth's mass.

Now focus on either one of the smaller masses. If you carry the Earth and a marble to the top of the drop tower and drop them, both will accelerate at the same rate.

Keep in mind that the magnitude of the acceleration of the Earth in the gravity field of really small objects is, well, really small. For the example being discussed here I'm not sure how big an object needs to be for us to be able to actually detect this side of the phemomenon of mutual gravitational attraction. We know the Moon IS big enough, and the ISS is not. I'm going to guess a few humdred kilometers.

In the make-believe world of Math such tiny things can't be ignored. In the real world of Physics and Engineering we ignore them all the time. It <b>is</b> still there, but who cares?

Sometimes we even neglect things that can be measured. But we are (or at least ought to be) always aware that we have ignored something, and understand why, or we risk forgetting to add it back in when circumstances no longer permit neglecting it.

Once you cross the line, you have to do BOTH sides of the problem and combine them to get the right answer.

Physics is more than math.

You know, it's been a long time since I've thought about some of these very basic issues. And I find it is fun to do so. The basics really are important. Thanks.

Regards,
LB

The basic issue here is how misuse of math or whatever can get results everyone is pleased with even though it is wrong. This problem is not limited to the above example but, rather is a fairly common and well established practice in physics and astronomy. There are a few "constants" and many math problems that need to be redone because of this problem.

I'm back from Phoenix. 62nd birthday party. My present from my son was the first demonstration of our latest ROPEngine. That was great.
Bee working on that sucker for 25 years. Finally got one running good.

I was unable to find the link to the gravity guy but have e-mailed him to get the link for the freefall desparity information. I was surprised to see the interest this little fluke generated.

mechanic,

The link for the disparity of free fall of objects:

home.wwdb.org/erik/fallingobjects/