Why won't the pendulum in my daughter's room stop swinging?

[Tsuga]

My sister bought my daughter a crystal for her window to make rainbows. I hung it up from the curtain rod when we arrived. It hasn't stopped swinging since we made her bed. I thought it kept getting agitated by moving things, nailing pictures, doors shutting etc. but tonight I was in her room because she said she could not get to sleep. I sat there for 15 minutes and no abating. The house is still. It is about 2"x3"X1" (w h d). It is hanging about 2.5 feet from the curtain rod. Still swinging now 10 min. later. Is that normal?

[Suzanne in ABQ]

Yup.  Totally normal.  If there is no friction to slow it down, it could swing indefinitely.  

 

If you watch, it will seem to change direction as the earth rotates beneath it.  Come to think of it, it may hit the window.  That will either dampen the swing, or break the window.  

[Arcadia]

Nope, 10mins is very long. I'll look for draft from the window. Our bedroom windows had a slight gap at the bottom before the guys checking units for defects help us close it tight by brute force.

[Elfknitter.#]

 

Sorry, seemed like it had to be said.

 

I will say the wiki on pendulums is interesting: https://en.m.wikipedia.org/wiki/Pendulum

[fraidycat]

Yup. Totally normal. If there is no friction to slow it down, it could swing indefinitely.

 

If you watch, it will seem to change direction as the earth rotates beneath it. Come to think of it, it may hit the window. That will either dampen the swing, or break the window.

When we went to the museum of natural history in San Diego, my kids sat and watched the giant pendulum several times for several minutes at a time. They said it was relaxing. :)

[displace]

Her bedroom is a pocket in space where physics rules don't apply.

[The Girls' Mom]

Her bedroom is a pocket in space where physics rules don't apply.

 

This is a common phenomenon in teen rooms I hear.  My own daughter's room developed a worm hole that sucks in *all lost things*.  Lose something at our house? Check dds room.  That's where it is.   :lol:  

[Mimm]

This is a common phenomenon in teen rooms I hear.  My own daughter's room developed a worm hole that sucks in *all lost things*.  Lose something at our house? Check dds room.  That's where it is.   :lol:  

 

Yep, for sure. My daughter's room produces matter out of thin air so that even if you clean it, it is messy within hours.

[gardenmom5]

the air in the house is not still.

 

eta:  there may or may not be a draft from the window.  if you have a heat source that circulates air - the air moves.  if people or pets move -the air moves.

even when our system/fan is off, I can feel a draft come from under a closed door (we have hardwood - and the doors still have clearance for carpet.)

when I go to the  temple  -there is one room I will sometimes just sit and enjoy.  it has a *massive* chandelier.  it slowly rotates back and forth, despite it's  size.  it's the air circulation  from the HVAC system.  there are no windows in this room.

Edited April 8, 2016 by gardenmom5

[Bluegoat]

Yup.  Totally normal.  If there is no friction to slow it down, it could swing indefinitely.  

 

If you watch, it will seem to change direction as the earth rotates beneath it.  Come to think of it, it may hit the window.  That will either dampen the swing, or break the window.  

 

There would be friction with the air.  Otherwise, it would be a perpetual motion machine and Tsuga could make a mint.

[Bluegoat]

I'd say there is a little draft there.  Most windows have them.

[JoJosMom]

My sister bought my daughter a crystal for her window to make rainbows. I hung it up from the curtain rod when we arrived. It hasn't stopped swinging since we made her bed. I thought it kept getting agitated by moving things, nailing pictures, doors shutting etc. but tonight I was in her room because she said she could not get to sleep. I sat there for 15 minutes and no abating. The house is still. It is about 2"x3"X1" (w h d). It is hanging about 2.5 feet from the curtain rod. Still swinging now 10 min. later. Is that normal?

 

FAIRIES!!!  Your new home has fairies and they live in your DD's room.  That's awesome, Tsuga!

[Tsuga]

Hah! We cannot definitively rule out fairies or aliens so we remain agnostic on those. It is probably above the vent for heating /air. I didn't think of that because it seems so heavy to be moved by a breeze but of course it is hanging on a string so that must be it.

 

Though, the idea that the demons who steal socks, five dollar bills, and phone chargers are accidentally nudging it as they pass through seems to have a lot of circumstantial evidence behind it as well.

[Tsuga]

There would be friction with the air. Otherwise, it would be a perpetual motion machine and Tsuga could make a mint.

Believe me I spent a good minute thinking this through--"We've known about pendulums for millennia, and we have to wind clocks... Gravity could not possibly be acting observably on such a small object... Could it?" I decided that such an alignment between a high gravity area, some other force of nature, etc. would be comsmically unlikely and decided to post here.

 

Wait... Not gravity, but the earth's rotation, obviously we see gravity act on small objects all the time.

 

It was 10 pm and I was getting a tired kid comfortable, I blame delerium.

Edited April 8, 2016 by Tsuga

[Southern Ivy]

Her bedroom is a pocket in space where physics rules don't apply.

Like the movie Interstellar. :) 

[Tap]

If the outside temperature is significantly different from the temperature inside (or even just direct sunlight), I would also theorize that the temperature change of the air in front of the window may create some movement.  

 

My first guess is a vent near by that is creating air movement. 

 

We used to live in a very tiny house that had a paddle lock hanging by the door.  Anytime someone walked thorough the door the lock would start swinging.  It could swing for over an hour, just due to the initial bump and air movements. 

Edited April 8, 2016 by Tap

[Suzanne in ABQ]

Nope, 10mins is very long. I'll look for draft from the window. Our bedroom windows had a slight gap at the bottom before the guys checking units for defects help us close it tight by brute force.

 

 

the air in the house is not still.

 

eta:  there may or may not be a draft from the window.  if you have a heat source that circulates air - the air moves.  if people or pets move -the air moves.

even when our system/fan is off, I can feel a draft come from under a closed door (we have hardwood - and the doors still have clearance for carpet.)

when I go to the  temple  -there is one room I will sometimes just sit and enjoy.  it has a *massive* chandelier.  it slowly rotates back and forth, despite it's  size.  it's the air circulation  from the HVAC system.  there are no windows in this room.

 

 

There would be friction with the air.  Otherwise, it would be a perpetual motion machine and Tsuga could make a mint.

 

 

I'd say there is a little draft there.  Most windows have them.

 

 

If the movement is circular or irregular, and/or the shape of the crystal is flat, or the string is short or wide like a ribbon, or the bob is lightweight, you might blame air currents. 

 

However, if the movement is straight back and forth, and the mass of the crystal is large compared to the string, and there is no friction at the pivot, then the movement is caused by gravity.  (potential/kinetic energy conversion)

 

2 1/2 feet is a long moment arm, especially if the crystal is hanging by a thin string with no friction at the pivot.  If the crystal is rounded in shape, and it's hanging by a thread, then air resistance is going to be negligible.

 

Yes, the pendulum will eventually stop, but it may take a long time.  

 

Yes, we wind clock pendulums, but clock pendulums are working against all the friction in the clock mechanism (not to mention energy losses in the sound of the ticking and gonging)  That is not a simple pendulum.  The fact that we only need to wind a pendulum clock once a day is a testament to just how long a pendulum can swing by itself.

 

10 minutes is not terribly long for a simple pendulum of this type to swing on its own.  

 

Tsuga, you may want to secure the bottom of the crystal to keep it from accidentally swinging into the window.  

 

 

(BTW, I have a degree in mechanical engineering, but it's been a long time since college.  I'm open for anyone who wants to convince me that I'm wrong about this.)

[EKS]

We have this set of fireplace tools that hang and one of them will swing for a *very* long time if it gets going right.  It's really trippy.

[Tsuga]

If the movement is circular or irregular, and/or the shape of the crystal is flat, or the string is short or wide like a ribbon, or the bob is lightweight, you might blame air currents. 

 

However, if the movement is straight back and forth, and the mass of the crystal is large compared to the string, and there is no friction at the pivot, then the movement is caused by gravity.  (potential/kinetic energy conversion)

 

2 1/2 feet is a long moment arm, especially if the crystal is hanging by a thin string with no friction at the pivot.  If the crystal is rounded in shape, and it's hanging by a thread, then air resistance is going to be negligible.

 

Yes, the pendulum will eventually stop, but it may take a long time.  

 

Yes, we wind clock pendulums, but clock pendulums are working against all the friction in the clock mechanism (not to mention energy losses in the sound of the ticking and gonging)  That is not a simple pendulum.  The fact that we only need to wind a pendulum clock once a day is a testament to just how long a pendulum can swing by itself.

 

10 minutes is not terribly long for a simple pendulum of this type to swing on its own.  

 

Tsuga, you may want to secure the bottom of the crystal to keep it from accidentally swinging into the window.  

 

 

(BTW, I have a degree in mechanical engineering, but it's been a long time since college.  I'm open for anyone who wants to convince me that I'm wrong about this.)

 

Thank you for your input! That is really interesting. The movement was back and forth, the mass of the crystal was large compared to the string (it was very thin plastic), but I seriously doubt that there was almost no friction at the pivot. There was probably quite substantial friction given that it was simply a plastic string tied around a curtain rod.

 

I will consider securing it somewhere. The main concern is that it could become a projectile in case of a very large earthquake... we are just crossing our fingers that our engineers knew what they were doing in these Seattle suburbs. Nothing hangs above the head, but we have objects above the bed toward the leg area (as that is the window).

[vonfirmath]

Like the movie Interstellar. :)

 

I want to see that again!

 

[Carol in Cal.]

You guys are all wrong.  It's a ghost, obviously.   With a message.

 

 

 

 

And the message is, "You're wasting time!"

Edited May 10, 2016 by Carol in Cal.

[zimom]

By the title I just knew you were talking about teen hormones and emotions  :)

[Peach]

If you are in an area with seismic activity that might do it. We are and tho we don't get movement we can feel, the spices in my cabinet slip around on the shelf (and sometimes fall off) often.

[PinkyandtheBrains.]

 

 

I vote aliens or fairies.

 

 

 

I wish the bedroom wormhole would suck all the clutter away too.