I think when you're holding the top the spring (slinky) is under tension. When you release the slinky the tension recoils the spring. The acceleration of the top versus the lack of acceleration at the bottom is a function of the center of gravity or center of energy or - - - . The guy demonstrated a few different types and the all seem to be suspended at the bottom, motionless.

Now I want a Slinky.

Y'know, people are like slinkies. Not much practical use but they sure are fun when you push them down the stairs.

 

Got a few new posts today:

 

Cool video. But not real. Still, it's cool.

 

Today's pick:

 

 

Simone Biles watch out!

 

 

I gotta admit, Boston Dynamics is pretty damn cool. Wonder if they are making any profits?

 

Like so many great things started in the US, they are being sold to a foreign company.

https://www.engadget.com/softbank-boston-dynamics-hyundai-motors-sale-080541059.html

 

The guys who made that video are "Corridor Digital." They do some pretty neat stuff (they're VFX Artists). How they made that video is kind of cool.

 

 

 

 

I remember trying to make something similar with my dad decades ago. I was trying to use an old auto ignition coil to get the high voltage discharge. We tried, but I can't say we ever had much success.

 

Without watching the video first, looks vaguely like a Hall effect thruster (link). Neat ideas, and have actually been used on real rockets/probes, though they don't generally create much thrust for the amount of power it takes to use one so they're usually reserved for when the probe has left our atmosphere.

 

Without watching the video first

Hope you gave the video a watch. Answers the question about feasibility in space to use ion thrust. Spaceship will need to carry a fuel source for the ions to push off of.

 

Hope you gave the video a watch. Answers the question about feasibility in space to use ion thrust. Spaceship will need to carry a fuel source for the ions to push off of.

Fear not! I eventually got around to watching it. A number of years ago I built a very crude one of these by "accident" (playing with a flyback transformer from an cannibalized CRT to generate >60kV sparks for a plasma speaker, as any reasonable person does in their spare time). Wasn't nearly as sophisticated - I spent a bit of time blowing pieces of paper around my workspace with the ion winds. Later in the project I melted an unreasonable amount of wire (turns out, plasma's hot!) until I found some of an appropriate gauge. Also discovered the hard way that the bright purple coloration of the plasma was due to ionization of nitrogen, which generates moderate quantities of UV.

 

That, "ionic wind" is from the early 18th century, " Francis Hauksbee, curator of instruments for the Royal Society of London, made the earliest report of electric wind in 1709 " From - https://en.wikipedia.org/wiki/Ion_wind

The first part uses a Wimshurst Machine, something I made many years ago, makes pretty big sparks, 2 1/2 to 3 inches in all humidity levels, and bigger ones when humidity is low. All by hand turning a crank. https://en.wikipedia.org/wiki/Wimshurst_machine

 

Anyone else see anything like this before? I DO remember "Mercury" batteries back in the 70;s and 80's.

 

I can only wish I spoke this language. This is pretty neat. I think so anyway.