Weird off-topic question........long

6 years ago

Sorry if this is the wrong place to ask this, but I couldn't think of anywhere else........except maybe a physics or "weird happening" forum. haha

I was in my bedroom the other day and noticed a reflected light on the ceiling, rhythmically going back and forth, back and forth fairly fast. At first I dismissed it as the sun shinning on some of my little wind chimes I have hanging in my bathroom....which is open to my bedroom (master bedroom and bath). The bathroom window lets tons of light shine in. Then it hit me, if that were the case, the spot of light wouldn't be so rhythmic unless one of the chimes was moving like that, which it wasn't.. I went into the bathroom and checked out the clock on the wall, thinking the light was somehow reflecting off the second hand. And the clock wasn't even in the sun.

I just couldn't figure out what was going on. I have to admit......it was sort of a "Twilight Zone" moment for me. I just couldn't figure it out. What could be so rhythmic??

I had to go fix dinner, and then went back to check in the bathroom again, and looked out the window........and there is my hanging solar lantern, swinging in the exact same timing as the second hand on my clock. So.......the mystery was partially solved. The light on the ceiling was moving in sync with the movement of that solar lantern (that I have on a shepherd's hook).

Well.......after the sun set, I sent back to the bedroom. The spot on the ceiling of course was gone, but that lantern was still in sync with the clock ticking. Hmmm.....

I have another one of these solar lanterns on a shepherd's hook outside my kitchen too. I looked at it, and it, too, moves in rhythm with a different clock's ticking.

So here's my question, besides WTF??? hahaha Is there anything in a solar powered device that would possibly cause this rhythmic movement? Even when there was a strong breeze yesterday, it didn't change this tic-toc-type movement. Maybe it's just that "perpetual motion" type thing?

When I told my husband about this, he was a little worried about me. hahaha It was a very curious experience, and seems to continue, since the solar lanterns keep this rhythmic movement going.

Any ideas? Many of you folks are used to thinking through problems, so I thought I'd ask you guys first. Honest.........I'm not crazy. (well, not totally). :)

Let me know what you think (about the movement of the lanterns.......not if I'm crazy or not).

Could it in any way be something to do with the type of battery/wiring in the light?

Thanks!

Featured Answer

Ron Natalie

6 years ago

Flutter is an odd thing. It might, it might not. Changing the length of the string or some other factor in the mix might also stop it.

Sort by:Oldest

Comments (9)

User
6 years ago
Aeroelastic flutter.

Rotate the hook 30 degrees.
catherinet
Original Author
6 years ago
Wow......thanks Jim. That sounds like a very likely possibility! I can't move the shepherd's hook right now. It's about 9 degrees out and the ground is frozen, but I'll do that when it warms up a little. Thanks for pointing me in that direction!
Related Professionals
Jacksonville General Contractors · McComb General Contractors · Toms River General Contractors · Oklahoma City General Contractors · Atlanta Home Remodeling · Ashland Home Remodeling · Hagerstown Home Remodeling · Jackson Home Remodeling · Jacksonville Home Remodeling · Austin Home Remodeling · Texarkana Home Remodeling · Madison Home Remodeling · Billings Home Remodeling · Tulsa Bathroom Remodelers · Santa Rosa Bathroom Remodelers
Stax
6 years ago
last modified: 6 years ago

Oscillation of a Simple Pendulum

This would explain why the pendulums would have fixed period that might coincidentally coincide with a ticking clock's sound.
catherinet
Original Author
6 years ago
Thanks Stax! I'll study that a bit. My mind has trouble understanding some of this stuff, but it sure is interesting. If it hadn't been for that reflected light racing back and force across my ceiling from the solar lantern, I would never have learned about this extremely interesting stuff that goes on all around us! Thanks again.
Stax
6 years ago
catherinet,

I'm not comfortable with my answer - however I'm also not comfortable with Jim Mat's.

We need someone else to weigh in with the "right" answer.
Ron Natalie
6 years ago
Actually both the flutter and pendulum are related. Flutter says that if you apply the right flow against something that's capable of movement, and it has some force that opposes that movement, you can in the right conditions get an oscillation (i.e., moving back and forth rather than just deflecting and staying there).

The pendulum stuff Stax links explains that if you have a pendulum that you start in motion (and it just requires gravity, not air), that the period (how long takes to swings back and forth) stays constant even when the amount its swing decreases. It also shows that the period is dependent on the length of the cord rather than the weight.

So a gust of wing could set it swinging like a pendulum. However, to keep it swinging you need either one of two things, strategically timed gusts (if you have ever seen a pendulum display in a museum, they usually use a timed electromagnet to keep pushing on the pendulum). However, if you have a steady wind, that wouldn't allow the pendulum to swing back except that there may be other forces in play (which would be the definition of flutter).

It is correct that it often doesn't take much disruption to stop the feedback loop that causes flutter (although just changing the point of attachment a bit may not be sufficient).
catherinet
Original Author
6 years ago
Thanks Ron! I'm finding this very intriguing, even if I don't completely understand it. I'm still going to try to move the shepherd's hook 30 degrees as soon as the ground thaws a bit (or maybe even more after that). . Do you think that would be enough to stop the flutter? All this stuff would be so much fun to learn lots more about, if half my brain wasn't dark. :)

Thanks again. You always give such good answers!
catherinet
Original Author
6 years ago
Thanks Ron. There's always something new to learn!