(2020-01-11, 12:40 PM)Chris Wrote: [ -> ]Surely the simple point is that LoneShaman said that the continued swinging of the pendulum was an indication of an atmosphere. Whereas in fact a pendulum will continue to swing in a vacuum, until it's stopped by friction at the point of suspension. And it will continue to swing for longer in a vacuum than it would in still air.
Well there was talk about an air vent - the discussion went rambling on. Honestly, I don't think there was anything like the evidence that LS is scientifically illiterate. The problem is that none of these scenarios are precisely specified.
If you saw a sign swinging, you would take that to mean there was a wind. Likewise if you saw a piece of paper rustling in a room you would suspect a draught of some sort.
David
(2020-01-11, 03:04 PM)David001 Wrote: [ -> ]If you saw a sign swinging, you would take that to mean there was a wind.
The whole point of that discussion was that - apart from the effect of friction at the point of suspension, which may be very small - a pendulum in a vacuum
doesn't need a force to be acting on it for it to continue to swing. That was what LoneShaman wouldn't accept. It doesn't sound as though you accept it either.
The bag was swinging because one of the astronauts had just hung it there, thus giving it some initial momentum. The nonsense about wind is just hot air.
(2020-01-11, 04:11 PM)Max_B Wrote: [ -> ]Fell about laughing as I reached the end of this paragraph I was reading in article on Wiki about Pendulums... 
We learned this stuff in the kids' playground. It was easy to hit yourself in the teeth if you were pushing someone else on a swing and didn't stand back after a hard push.
