Newton's Cradle in vacuum

Toggle sidebar Toggle sidebar
JEDI

JEDI

Lifer
Sep 25, 2001
29,391
2,737
126

In my mind, the balls slow down till it completely stops due to air friction and energy expended due to sound from the balls hitting each other.
In a vacuum, there is no air friction nor is there sound.

So in a vacuum, it should swing indefinitely.
Nope. Not even close :eek:
 
Last edited:
  • Like
Reactions: SteveGrabowski
BoomerD

BoomerD

No Lifer
Feb 26, 2006
65,607
13,987
146
JEDI said:

In my mind, the balls slow down till it completely stops due to air friction and energy expended due to sound from the balls hitting each other.
In a vacuum, there is no air friction nor is there sound.

So in a vacuum, it should swing indefinitely.
Nope :eek:
Click to expand...
Now try it in zero gravity...
 
Charmonium

Charmonium

Lifer
May 15, 2015
10,321
3,406
136
My guess is that a minute amount of heat is generated and radiated via photons. Also it seems the pendulum motion is gradually transferred to all of the balls. The latter should be the dominant effect.

If you find a definite answer, pls share.
 
  • Like
Reactions: Ken g6 and biostud
biostud

biostud

Lifer
Feb 27, 2003
19,453
6,504
136
Charmonium said:
My guess is that a minute amount of heat is generated and radiated via photons. Also it seems the pendulum motion is gradually transferred to all of the balls. The latter should be the dominant effect.

If you find a definite answer, pls share.
Click to expand...
Yes, I would think that the kinetic energy would be converted into thermal energy over time.
 
  • Like
Reactions: igor_kavinski
Red Squirrel

Red Squirrel

No Lifer
May 24, 2003
69,705
13,329
126
www.betteroff.ca
That was interesting, I did figure it would go much longer but it does kind of make sense that the air resistance is minimum anyway compared to the strings and also the actual impact. I wonder how this scales, like if you made a giant cradle the size of a building perhaps the air resistance would play a bigger role as there is much more travel time. But then the strings are also bigger so would also create more resistance.
 
JEDI

JEDI

Lifer
Sep 25, 2001
29,391
2,737
126
igor_kavinski said:
He trusts the Force. Still alive, isn't he?

Crashed planes. Had plenty of other accidents. The Force keeps him strong and healthy as a horse!
Click to expand...
A girlfriend 1/2 his age also helps give incentive to stay healthy
 
GodisanAtheist

GodisanAtheist

Diamond Member
Nov 16, 2006
7,890
8,983
136
Heat/sound/etc energy loss is probably nothing vs resisting gravity each time the pendulum swings.
 
SteveGrabowski

SteveGrabowski

Diamond Member
Oct 20, 2014
8,581
7,204
136
JEDI said:

In my mind, the balls slow down till it completely stops due to air friction and energy expended due to sound from the balls hitting each other.
In a vacuum, there is no air friction nor is there sound.

So in a vacuum, it should swing indefinitely.
Nope. Not even close :eek:
Click to expand...
I was thinking it was losing elastic energy from the collisions deforming the balls and then them bouncing back but nope, turns out it was mostly lost in the suspending wires. On a related note for anyone trying to understand physics:

 
Fenixgoon

Fenixgoon

Lifer
Jun 30, 2003
32,882
12,158
136
JEDI said:

In my mind, the balls slow down till it completely stops due to air friction and energy expended due to sound from the balls hitting each other.
In a vacuum, there is no air friction nor is there sound.

So in a vacuum, it should swing indefinitely.
Nope. Not even close :eek:
Click to expand...
I was expecting it to go on a lot longer than it did
 
You must log in or register to reply here.

TRENDING THREADS

COMPANY
RESOURCES
FOLLOW
Top Bottom