# Physics

As a child 60 odd years ago I witnessed the daredevils amongst us swing on park swings which comprised of wood seats and chains gain enough momentum to go completely over the top. A guy has posted on Physics-Astronomy that he believes it is not possible and I have not recalled this properly.  I have questioned several of my friends and they remember it too. I don't know physics I just am learning about astronomy at this late stage in my life. How can I convince him this is true in a simple fashion because I truly witnessed this happening many times?
d-glitch

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This from Myth Busters:  http://www.discovery.com/tv-shows/mythbusters/mythbusters-database/swing-all-the-way-around/

The only way this could happen with a chain swing would be if there was some kind of propulsion on the rider of the swing.  They also did this on Mythbusters.

It is not physically possible.
Oympic athletes spin round quite well on those parallel bars. Once they have the momentum worked up by bringing their knees in a couple of times it looks like most of their effort is spent in holding on while they go over the top. On a swing you would just need to be brave enough and keep your lunch inside.
Perhaps one of this new generation of free-runners would be mad enough to try on a swing.
Gymnasts are connected to the bar by stiff arms rather than floppy chains.  Of course they can modulate the stiffness.  But this is more like a wooden swing.

If the distance between the CM of the swinger and the pivot is h, then the distance between the swinger's high and low points is 2h.
For the swinger to reach the top, his kinetic energy at the bottom ( ½mv² ) must be greater than the change in gravitational potential ( 2mgh).
SOLUTION

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And as soon as the chain starts wrapping the center of gravity would shift even more speeding up the person on the swing.

This would get real ugly real quick.
That was something we considered as teenagers and one of the reasons we didn't try. Another reason was that the swings were set in asphalt which would have made a very uncomfortable landing if something went wrong.
Here's one that goes over. Maybe not obeying the rules of how to use a swing properly, but neither is being too old for the playground, standing up, or going over the top.
If I'd seen this as a child I'd say I saw someone swing right over:
https://youtu.be/0F9bSS4zgHY
SOLUTION

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brett lee

The main way this could occur with a chain swing would be if there was some sort of drive on the rider of the swing. They likewise did this on Mythbusters. otherwise its not conceivable.
When you say drive, do you mean someone pushing them to help increase the swing?
Surely that would be acceptable for an answer to this question.

Or are you suggesting a rotating motor turning the bar that the swing hangs off like an axle?
Here is a great discussion on this topic:  http://ask.metafilter.com/232992/Extreme-playground

And here is video of someone who manages an over-the-top with a chain swing:  https://www.youtube.com/embed/c0zAzqSa-5o
[He needs a compressed air/water jet engine.]
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