Naked Science Forum

General Science => General Science => Topic started by: vixon on 24/06/2015 07:32:14

Title: Why didn't the whole slinky hanging in a slow-mo video fall, why jus th tp start
Post by: vixon on 24/06/2015 07:32:14
As title says, the top of the spiral spring slinky toy started first.

My guess, as wiki says too, is gravity pulls the whole object down - all atoms get pulled.

My guessing answer is that because the atomic bonds to it's above neighbor were being pulled fully already by gravity, gravity had no effect on them but the top atoms fields.
Title: Re: Why didn't the whole slinky hanging in a slow-mo video fall, why jus th tp start
Post by: Colin2B on 24/06/2015 09:03:41

My guess, as wiki says too, is gravity pulls the whole object down - all atoms get pulled.

My guessing answer is that because the atomic bonds to it's above neighbor were being pulled fully already by gravity, gravity had no effect on them but the top atoms fields.
If you are thinking of a slinky suspended by the top and then released, you are on the right track.
My analysis would be that the slinky is a spring and when it is suspended it's own weight pulls it stretched. When the top of the slinky is released 2 things happen . First the whole slinky begins to fall, but then then because it no longer feels the pull of gravity (it is in free fall) the spring begins to contract and the 2 ends start to move towards each other. These 2 motions combine so that the top and bottom of the slinky fall at different rates, the bottom falling more slowly.
Title: Re: Why didn't the whole slinky hanging in a slow-mo video fall, why jus th tp start
Post by: vixon on 24/06/2015 21:28:05
Oh now I get it. Gravity pulls it apart like so, and when release it, gravity pulls all of it, BUT it contracts since gravity across it is even everywhere, just like a totally-contracted slinky would fall, it has no reason to stay un-contracted.