Slinky's shenanigans - Solve the engineering

@ramani-VR4O43 • Oct 20, 2024

Oct 20, 2024

1.2K

Perpetual motion or free fall? It is walking downhill.

The bottom of the jaw drops instantly on seeing this 'antigravity antics of Slinky. The disbelief continues even after seeing the explanation. The wonders of mechanics!
<a href="https://pmpaspeakingofprecision.com/2012/06/22/the-bottom-of-the-slinky-doesnt-fall-immediately/" target="_blank" rel="nofollow noopener noreferrer">The Bottom of The Slinky Doesn’t Fall Immediately- | Speaking of Precision Blog</a>

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Kaustubh Katdare

@thebigk • Jun 28, 2012

I'm totally amazed by this! The explanation that comes to my mind is like this -

Once the top end is released, the slinky begins to contract - the tension tries to bring the bottom end up with an equal force ( 😨 😕 ) as that applied by the gravity, which keeps the bottom steady until the slinky stops the upward force.

Slow motion photography is surely making us rethink stuff! I'm moving this to mechanical engineering section for some constructive discussion.
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Ramani Aswath

@ramani-VR4O43 • Jun 28, 2012

The_Big_K
Once the top end is released, the slinky begins to contract - the tension tries to bring the bottom end up with an equal force ( 😨 😕 ) as that applied by the gravity, which keeps the bottom steady until the slinky stops the upward force.
You are right. The bottom is falling. However it is also moving up at the same speed. So there is no net movement till the whole thing bunches up. Then the entire mass falls together.
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zaveri

@zaveri-5TD6Sk • Jun 29, 2012

somehow i feel that centrifugal force developed by the rollers of the treadmill is affecting this.

now considering that the direction of the treadmill was reversed, then in which way would the slinky move. ?
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Ramani Aswath

@ramani-VR4O43 • Jun 29, 2012

zaveri
somehow i feel that centrifugal force developed by the rollers of the treadmill is affecting this. now considering that the direction of the treadmill was reversed, then in which way would the slinky move. ?
This toy can only move down a slope or steps. If the treadmill is stopped, it will still go down the slope and stop after reaching the end. If it is reversed the toy will reach the end and fall off.
If you keep it on the top step of a flight of stairs and bring down the top end to the next step, it keeps going down from step to step till it reaches the bottom. It does not violate the second law and climb up the slope or steps.
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Amith Gupta

@amith-gupta-8xdMSE • Jul 4, 2012

gosh.. i played with this thing for soo many years. ! mind boggling mechanics inside !😲
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Ramani Aswath

@ramani-VR4O43 • Jul 4, 2012

So did I. I am now trying to get one allegedly for my grand daughter, though I suspect that the grandfather is the one who is going to hog it!
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