15th September 2004 - 07:54 PM
QUOTE (z+Sep 15 2004, 07:03 PM)
Other possibilities for causality are a gravitational interaction between the solder and the resin, or some type of coriolis force.
Gravitational interactions would never cause rotation. Besides in this case they are TOO small. The Corilis force is an inertial force, acting to the right of the direction of body motion for counterclockwise rotation of the reference frame or to the left for clockwise rotation, so it is also not applicable in this situation.
15th September 2004 - 09:16 PM
Although it may not be applicable to this situation due to magnitude, gravitational forces are implicit in the rotation of the earth and other planits about the sun. No gravity, no rotation.
The same for coriolis forces. They may be too small to make a difference, however the space station is a rotating reference frame, so coriolis forces exist.
15th September 2004 - 09:44 PM
Surely we have a situation here simular to any satalite around a body there is some force holding the solder to the surface otherwise in no gravity it would have been thrown off in a straight line.
Also notice the the orbit path changes. It is obvious that the heat is causing the rotation as it speeds up and slows down as the wire is heated.
Remember theres no gravity and theres a slight pull to the left by the collection device.
15th September 2004 - 11:38 PM
as resin vapour is emitted when in normal use it is possible that the resin is emmited via small holes thus providing a driving force. which could explain the heat/speed relationship
why is the orbit path changing? this could be explained by escaping gas
I would have liked to see the exp run longer as all the fluids would have eventually be driven off.
17th September 2004 - 06:49 PM
My explanation is this:
First the solder heats up, and due to surface tension it draws itself into a ball. Next through slight movement, either from air or a from the hand of the astronaut there is a slight movement of the ball of rosin. There is no convection in a microgravity environment, so the rosin starts to vapourize at the hottest part. The hottest part is the area which has been in contact with the soldering iron the longest. Since there is slight movement in the solder already there will be a leading edge which has just contacted the soldering iron and a trailing edge which has been in contact with the soldering iron the longest. Since the trailing edge is the hottest it will vapourize and give the ball of rosin a small amount of thrust. It would look like burning a tire on pavement, the tire surface rubs over the ground but only smokes when it has nearly left the ground.
That's my best guess anyway,
17th September 2004 - 11:57 PM
Yes - I've seen this before. However, it didn't require the environment of a space station. Many years ago, as an intern, I had to tin the leads of a couple hundred leaded resistors. I dipped the leads of the resistors into a dish of liquid rosin flux and then poked the leads into a crucible of molten solder. The rosin sizzled and rolled up into little spheres which then whizzed across the surface of the solder. The paths of the spheres varied - some would dart across the solder and bounce off the walls of the solder-pot while others spun around in circles or spirals. Needless to say - the experimental set-up is pretty easy if one actually wants to experiment and truly figure out the underlying mechanisms. And you don't even need to be an astronaut.
18th September 2004 - 01:36 AM
I dont agree that convection has anyting to do with gravity also if you download the longer clip it can be clarly seen that the resin speeds up as it gets hotter indicating that the amount of heat is important.
I will try that experiment later.
21st March 2005 - 12:10 AM
QUOTE (ARtone+Sep 18 2004, 01:36 AM)
I dont agree that convection has anyting to do with gravity
AR: please define "convection" without referring to gravity.
weary scientist hit the nail on the head, nothing more needs to be said.
21st March 2005 - 12:45 PM
Somebody needs to try and repro this effect on a vomet comet. Also, it would be nice to have the experiment tried with a fixed soldering iron.
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