Slinky Drop! Make your predictions. Someone needs to do this on the ISS - I think in zero gravity the wave front would travel back & forth for a long time once the two ends meet in the middle.
What the heck I guessed "Top" where's the answer, arghhhh! I played with a slinky a lot in my younger day so my guess comes from experience not physics know how!
Anyone who refers to the bottom end of a slinky as "sitting there minding its own business" is alright in my book.
The old man is one awesome Aussie physics professor, would have loved to study under him. I trust, Trebuchet, you were able to follow through after the video to the next one showing the answer?
That is really cool! Thanks, Mark. I got it wrong on the first one (slinky alone) but after watching the answer, I got it right on the second one (tennis ball attached).
Well, there's the long sought anti-gravity device at last! Make an extra strong slinky about 100 miles high and hang your car from it (with a propellor to drive it) and you'd probably make it all the way to the video store to pick up the latest science fiction flick before alighting.
Like Daniel, I got question one wrong but question two right. I watched all four videos before answering, though, so no points for me there even though I answered correctly.
After watching the answer to #1, it was obvious that the answer to #2 would be the same. The same physics applies.
...And if you put the top of the slinky high enough (say 22,000 miles) it never drops, and you can climb it into orbit...
Of course it was obvious. However, denying the painfully obvious when it comes to science is a growth industry.
The idea of a "sky hook" was once popular among the fringe crowd. It runs afoul of the Earth's rotation and weather. And it still takes a lot of energy to climb the cable, which must be very large itself if it is to support any significant weight. Note that while the slinky works regardless of the weight at the bottom, it stretches more and more as the weight increases. The very act of putting a weight on the cable to climb up it will change the orbital dynamics of the cable itself and of the orbital satellite at its top. It would be a great idea for a fantasy story, if fantasy writers were not already enamored of teleportation.
You need the center of gravity at that altitude, not the top. Artur C. Clarke's Fountains of Paradise is about this exact topic. The orbital dynamics are not a big problem. The usual proposal is to use a counter weight moving opposite the load, along with normal orbital control for a geosynchronous satellite. The real problem has been strength of materials. Until recently engineers have lacked a material strong enough to support its own weight from space, let alone carry a load. Some of the new materials are past the break even point, but are not currently practical for long cables. Tom
At some point they'll genetically engineer spiders 40 feet long to spin genetically engineered silk cable to meet that need, but it will take longer to solve the problem of what to feed them.
That was one of the very first "Internet Videos" that I remember. Back when a flash-based singing banana or a frog in a blender where a riot. For a space anchor, we could use an asteroid parked in one of the L points. For propulsion, a ground based laser combined with microwave emitter to transmit energy to the "elevator". Of course, the cable is made up of Buckyballs !
