Recent content by RobertGC

A study found the upcoming Square Kilometer Array(SKA) could detect an airport radar 200 lightyears away: There are 260,000 stars within 200 lightyears of Earth. Bob Clark

On this seminar series: Technosignature seminar series. https://seec.gsfc.nasa.gov/News_and_Events/technosignatureSeminars.html I found a talk: Simulation of the Earth's radio-leakage from mobile towers as seen from selected nearby stellar systems Ramiro Saide, SETI institute January 17...

I’ve seen reports of creating a lunar radio telescope for long wavelength observations for astronomical purposes, though not for a SETI search: Building telescopes on the Moon could transform astronomy. The current race to the Moon is opening up opportunities for lunar astronomy. By Ian...

A problem with the SETI search is it looks for a specific radio frequency and even worse it has to be directly pointed at us to be detectable. We can’t from Earth just try detecting normal radio signals like we put out with radio, television, cell phones, etc. because from other planets it...

If the light weight is descending under gravity then the analysis and the equations become more complicated than the case where it is assumed to travel in a horizontal plane. Robert Clark

I’m informed in the conical pendulum case the total force of the tension force along the string and the gravitational force downwards is horizontal, so absent frictional and air drag forces the pendulum bob will rotate in a horizontal circle. Then your analysis should be valid. Still, as far...

Another question. Will the small weight also descend due to gravity while it is rotating? If so, will angular momentum still be conserved in such a scenario? I’ve tried looking this up on the internet and not gotten a definitive answer on this. If it does descend, then the equations will...

Putting r and r0 in the right spots the equation becomes: $$\frac{1}{2}{v_0}^2 + \frac{Mg}{m}r_0 = \frac{1}{2}v_t^2 + \frac{Mg}{m}r = \frac{1}{2}{(\frac{v_0}{r})}^2r_0^2 + \frac{Mg}{m}r$$ When you subtract the two kinetic energy terms from each other and two potential energy terms from each...

Thanks for that. The set up for your equations looks valid. Only, the issue with the r and r0 would mean it’s a cubic in r. Rather unexpected. I would love to see an experimental demonstration of how it looks. Robert Clark

There may be a problem with this last equation. Using ##v_t = \frac{v_0r_0}{r}##, then in the last equation the r2 and the r02 should be in the reversed positions. Robert Clark

If it does reach a minimum radius and start growing again, then presumably once it reaches again a maximal radius it will start decreasing again. Then the appearance should be of the heavy weight periodically going up and down, in concert with the smaller weight going in and out, instead of the...

Yes. Because the length of the rotating string is shrinking the path of the smaller weight can not remain circular. I have a question about the calculation in post #6 however. It would seem there should be a solution for r depending on time. But the equation provided only has 2 or only 1...

Yes. I was assuming it would remain circular. A more complex physics problem if it did not! I don’t think the heavy weight would always remain fixed. For instance suppose the heavy weight was, say, a hundred times that of the lighter weight and you only rotated the lighter weight at an initial...

You have a rope hanging over a fixed support with a heavy weight at one end and a lighter weight at the other end. You set the end of the rope with the lighter weight spinning in a circle and let the heavy weight end fall under gravity. As the heavy end falls the length of the rope that is...

Thanks for that. Quite interesting. Robert Clark