1
$\begingroup$

Not a physics person but curious about something going on and hoping someone can explain.

I have a kitchen witch hanging from my kitchen ceiling on some fishing line and it’s constantly swaying and moving about even though there is absolutely no air flow in the room (no windows open, no fans or aircon on) there is a plant right beside it and it’s not moving so there’s no breeze what so ever.

Just wondering what causes this? I personally don’t believe in ‘supernatural’ stuff so I just want to know what the logical explanation is :)

Use to be a science-buff in school so really interested!

$\endgroup$

closed as unclear what you're asking by Kyle Oman, user191954, Aaron Stevens, ZeroTheHero, Emilio Pisanty Mar 1 at 14:11

Please clarify your specific problem or add additional details to highlight exactly what you need. As it's currently written, it’s hard to tell exactly what you're asking. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

  • 4
    $\begingroup$ It's difficult to tell for sure what makes the "kitchen witch" to move in your case. One possible explanation would be even though no fans/aircons/open windows there are still some flows of air in the room. Different parts of the room have slightly different temperatures and that results in convection. The plant nearby does not sway because it's oscillations just damp/stop very quickly. $\endgroup$ – lesnik Mar 1 at 12:30
  • $\begingroup$ It is possible that the fishing line may twist with changes in temperature due to sunlight or light bulbs. $\endgroup$ – Keith McClary Mar 2 at 5:32
5
$\begingroup$

If the object hanging off the ceiling is light enough, just convection flow of air can constantly nodge it. I don't know exactly what you mean by "kitchen witch" or how the setup is arranged, but I have a hunch that's what's happening.

$\endgroup$
  • $\begingroup$ I think convection may be the cause! Thank you! And a kitchen witch is a witch doll you hang near your stove to ‘stop the pots and pans from boiling over and causing fires’ Silly old wives tale from the Scandinavian/European culture :’) $\endgroup$ – Rhiannon W Mar 1 at 13:06
  • $\begingroup$ Wow, that's undoubtedly the most ridiculously awesome thing I've heard in a while. You're welcome by the way. See you around. $\endgroup$ – TechDroid Mar 1 at 13:25
2
$\begingroup$

It is a relatively light object suspended on a string, which is moving. Thus some force must be acting on it. By far the most probable force is the air around it. But as you say, there is no breeze. So most likely it is turbulence in the air flow cause by the movement of people in the room (and maybe small airflows through bad isolation). Why is the plant not moving? Likely because the stems of the plant are harder to move than the pendulum-like object you have made of the kitchen witch.

But since you were a science-buff, what you of course have to do is conduct an experiment to test the supernatural force of your kitchen witch. Try finding an object of similar volume and mass, and suspending it in the same place. If it does not move, then your witch might possess magical properties! In that case, further experiments should be done. But if it does move, it would support a simple physical cause, such as our theory that it's simply an airflow too weak to move the plant (and too weak for you to feel).

$\endgroup$
  • $\begingroup$ Your experiment technically doesn't say whether or not it's air flows. You're basically saying if one object moves then we don't know why, but if two objects move then we know it is air flow. If you wanted to test air flow you would need to surround the object somehow to reduce air flow around it $\endgroup$ – Aaron Stevens Mar 1 at 12:48
  • $\begingroup$ Completely true, an assumption of the experiment is that the witch either moves due to supernatural causes or the most likely physical cause (air flow). The suggested experiment was simply a suggestion for how to work with the question using the scientific method rather than trusting some people on the internet. Note that I also didn't say that it "shows" that the cause is air flow, but rather supports it. $\endgroup$ – Codename 47 Mar 1 at 12:55
  • $\begingroup$ It doesn't support air flow. It just supports that it isn't unique to the "kitchen witch". The experiment shows nothing about air flow. If you want to teach people about the scientific method, then that should involve proper experiment design to test the proposed hypothesis. $\endgroup$ – Aaron Stevens Mar 1 at 12:59
  • $\begingroup$ Thank you everyone! I may just try a similar experiment, just for fun! $\endgroup$ – Rhiannon W Mar 1 at 13:04
  • $\begingroup$ @AaronStevens, I did not think the situation needed a completely technically explicit answer, but you are of course completely correct. I have edited the question to be more precise. To be explicit, the hypothesis tested would be "The witch moves due to supernatural forces not shared by a common physical object", which could be rejected if another object moves the same way. This would support a hypothesis that there is a natural cause. The best guess for which cause would then be air flow. $\endgroup$ – Codename 47 Mar 1 at 13:09

Not the answer you're looking for? Browse other questions tagged or ask your own question.