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Dr. Bob is Robert Hsiung, MD,
bob@dr-bob.orgShown: posts 57 to 81 of 95. Go back in thread:
Posted by 10derHeart on April 24, 2005, at 16:57:09
In reply to 10derheart i know you know how to play! (nm), posted by anastasia56 on April 24, 2005, at 15:40:51
Posted by Damos on April 24, 2005, at 17:12:15
In reply to Re: Yeah, but...having shyness attack.. :-( (nm) » anastasia56, posted by 10derHeart on April 24, 2005, at 16:57:09
Posted by alexandra_k on April 24, 2005, at 18:50:10
In reply to Re: Yeah, but...having shyness attack.. :-( (nm) » anastasia56, posted by 10derHeart on April 24, 2005, at 16:57:09
And I'm sure Damos will give you a push.
Incase anybody knows...
Is it possible to swing right round over the top?
Or will you get up there in the air and then just splat down again?
Or is either option somehow prevented?
I worry about this a lot...
Posted by alesta on April 24, 2005, at 19:34:08
In reply to Ammmmy, Ammmmy...hurry up! (nm), posted by anastasia56 on April 24, 2005, at 15:37:22
hey, y'all, no, that's ok..i'm just gonna sit over here on this tuft of grass with 10derheart and do a bit of people watching..:)
Posted by Damos on April 24, 2005, at 19:49:07
In reply to Re: Well, come join me on the swings then... » 10derHeart, posted by alexandra_k on April 24, 2005, at 18:50:10
> And I'm sure Damos will give you a push.
I'd love to :-)
>
> Incase anybody knows...
>
> Is it possible to swing right round over the top?
> Or will you get up there in the air and then just splat down again?
> Or is either option somehow prevented?
> I worry about this a lot...delving way, way back to my physics days there are a combination of forces at play here, centripetal and centrifugal. In theory yes it is possible if the required amount of force (momentum) could be created. The mens high bar in Olympic gymnastics is an example. The key difference being that on the swing the weight is on the circumference not toward the centre as with the gymnast. Think about trying to roll a tyre that has a big lead weight stuck in it. As you try to roll it the weight makes it harder and harder to roll the higher it gets until it gets pst the vertical where the weight begins to act in your favour due to gravity and accelerate downwards at 9.8m per second thereby creating enough momentum to push it up the otherside.
Does that make any sense? Suffice to say, you don't really need to worry Alex, that amount of force required to push an adult over the top would be considerable. You'd probably be lucky to swing through an arc of 270 degrees.
Posted by Damos on April 24, 2005, at 20:15:45
In reply to Re: Ammmmy, Ammmmy...hurry up!, posted by alesta on April 24, 2005, at 19:34:08
Posted by alesta on April 24, 2005, at 20:25:09
In reply to Okay, just glad you're here =0) (nm) » alesta, posted by Damos on April 24, 2005, at 20:15:45
Posted by alexandra_k on April 24, 2005, at 20:39:29
In reply to Re: Well, come join me on the swings then... » alexandra_k, posted by Damos on April 24, 2005, at 19:49:07
Phew!
I used to have nightmares about that!
Posted by Susan47 on April 24, 2005, at 21:34:54
In reply to Re: Well, come join me on the swings then... » 10derHeart, posted by alexandra_k on April 24, 2005, at 18:50:10
Of whether or not you can swing right 'round, over the top. My beanie tells me, and I might be wrong but I think you'd have to have an awful lot of speed, depending on how much you weigh I think the speed would differ, how much would get you round that is. Otherwise at normal swinging speed I think you'd slow down and get exactly half-way round, that is at the zenith of the half-circle, and,!splat! You girls remember riding a boy's bike and missing the pedal? you know what that FEELS like? So don't try it.... the swing or the bike ... but I'm probably wrong about the swing. You'd have to be strapped in, too. But I know you can push them up around, kids still manage to do that even with the super-high sets and the heavy chains. They must do it together, it's gotta be a group activity. Like pushing over mailboxes and tipping cows and outhouses.
Posted by Jai Narayan on April 24, 2005, at 21:45:37
In reply to Re: scarng me now, Damos » sunny10, posted by Damos on April 19, 2005, at 17:34:23
my dear damos, I can't believe I could have been hiding from your lovely call...
If I had been here I would have come out at once and joined in the naughty fun.
so what do we do now?
at your service...
Ja*
Posted by Damos on April 24, 2005, at 22:11:17
In reply to naughty fun...let the games begin...:), posted by Jai Narayan on April 24, 2005, at 21:45:37
You were probably just being shy and all. The only rules are to do whatever it is that makes you truly happy. Very glad you're here with us.
Posted by Susan47 on April 24, 2005, at 22:20:11
In reply to Re: naughty fun...let the games begin...:) » Jai Narayan, posted by Damos on April 24, 2005, at 22:11:17
Do what truly makes me happy? I would grab a warm, sweet, sexy man and cuddle with him under the blankets, facing the fire, spooning you know, naked under the blankets. Feeling the heat and the warmth of each other and the fire. And we would be telling each other lovely, loving, kind and exciting thoughts. Things about the nature of the universe and the meaning of life. I suppose I stopped participating in the game, I'm being lulled by my imaginary lover.
Posted by Damos on April 24, 2005, at 22:25:21
In reply to Re: naughty fun...let the games begin...:), posted by Susan47 on April 24, 2005, at 22:20:11
Warm - nah
Sweet - nah
Sexy - so way, way nahGuess I'm safe then, phew? Might just go climb a tree or something, just in case. Look out Lar.
Posted by Larry Hoover on April 24, 2005, at 22:33:32
In reply to Re: Well, come join me on the swings then... » 10derHeart, posted by alexandra_k on April 24, 2005, at 18:50:10
> And I'm sure Damos will give you a push.
>
> Incase anybody knows...
>
> Is it possible to swing right round over the top?
> Or will you get up there in the air and then just splat down again?
> Or is either option somehow prevented?
> I worry about this a lot...You can swing too high, and because the chains are flexible, there is danger in swinging above the horizontal.
A stationary swing is set in motion by moving laterally. The tension of the chain pulls the lateral motion into an arc, and as a result, you get lifted above the starting position. This lift is potential energy, which is really the option for gravity to pull you down again. As you fall down, you pump your legs, and you increase the height of the forward arc. This lifts you higher, and potential energy swings you back again. Kick, swing, kick, swing, and the higher you go.
If you picture being at the maximum height on the backswing, your kinetic energy of motion is completely turned into potential energy (you stop going back, and for an instant, you haven't started going forward yet). At that instant, the force of the chain holding you in the arc is at its minimum. As you start to move forward, your potential energy turns to kinetic energy again, and you pick up speed until you're at the very bottom of the arc. At that point, the force of the chain pulling you in towards the centre (centripetal acceleration is the result of that force) is at a maximum. As you rise forward, kinetic energy again turns to potential energy, and the tension on the chain goes to a minimum again.
The mathematical relationship of the tension on the chain (the inward force that keeps you from flying off in a straight line) varies as a trigonometric function of the angle. At exactly 90 degrees forward motion (true horizontal), your forward motion goes precisely to zero.....and if your kinetic energy goes to zero at exactly that point, you are completely weightless.....for an instant.
The key point to consider is that the tension on the chain also goes to zero at this horizontal extension, if your upwards motion stops too. If you're not moving, it's not pulling you inwards, for that instant, either.
If you go above that critical 90 degree juncture, the chain tension never goes to zero. Instead, it starts pulling you backwards again. If it pulls you backwards while you're still going up, the chain will go slack when gravity starts pulling you back down. You won't be travelling in an arc any more. (Mathematically, you'll follow a secant to the arc.)
When I was a kid, we called that "getting the bumps". The chain sags, and you literally fall free for an instant, until the chain snaps to full tension.
If you are not careful, rising about 3 degrees above the horizontal is sufficient to risk causing you to fall off the swing seat, and as the chains snap taught again, your grip will be broken, and you will tumble off, backwards.
Lar
Posted by alexandra_k on April 24, 2005, at 22:42:30
In reply to Re: Well, come join me on the swings then... » alexandra_k, posted by Larry Hoover on April 24, 2005, at 22:33:32
:-(
Well now my nightmares will probably return.
But I was kinda more worried about falling splat on the bar. Like Susan said. Why do guys bikes have that bar? I would have thought it would have hurt a guy even more to go falling on that bar...
Posted by alexandra_k on April 24, 2005, at 22:43:24
In reply to naughty fun...let the games begin...:), posted by Jai Narayan on April 24, 2005, at 21:45:37
Aw, Jai you missed the skinny dipping.
Still, we could go again if we can lure Susan and Mr XXX out from under that blanket.
Posted by alexandra_k on April 24, 2005, at 22:44:47
In reply to Susan's Dumb-*ss guess » alexandra_k, posted by Susan47 on April 24, 2005, at 21:34:54
Tipping cows!
I have never ever done that - but I saw it on the movie Heathers. It looked pretty funny - but I felt bad for the cow.Oh Susan, you are getting me thinking about you know what again...
Posted by Larry Hoover on April 24, 2005, at 22:59:35
In reply to Re: Well, come join me on the swings then... » Larry Hoover, posted by alexandra_k on April 24, 2005, at 22:42:30
> :-(
> Well now my nightmares will probably return.No, really....instinct protects you. That point of zero g's, at true horizontal, is usually enough to trigger the "I think I'm high enough now" feeling. Going a little past that (which can happen when you go from leg extension and back out, to full upright, at the point of furthest forward motion), gives you the feel of zero gravity, and a little freefall. That's where your instincts kick in. Only people without sense for consequences carry on past that.
BTW, it's that motion from full extension to sitting upright that drives you up. It's the same effect as that of a skater pulling in her arms for a spin. Pull the weight closer to the center of the arc, and the velocity increases (and thus, height). It's like shortening the pendulum, while having a longer pendulum's momentum. The only way for the pendulum to accomodate that is to increase the height of the arc.
Enjoy the swings. They're *nearly* foolproof. I.e., only a fool could mess it up.
Lar
Posted by gardenergirl on April 25, 2005, at 6:48:55
In reply to Re: Susan's Dumb-*ss guess » Susan47, posted by alexandra_k on April 24, 2005, at 22:44:47
Been there, done that. ;)
gg
Posted by sunny10 on April 25, 2005, at 9:03:53
In reply to Re: Well, come join me on the swings then... » alexandra_k, posted by Larry Hoover on April 24, 2005, at 22:59:35
when I was a kid, I was the skinniest little thing you ever saw.
I looped the swings...but I took gymnastics, too. The trick was that I had to use my legs, walking it across the top against the bar to stop the "chain slack" that Lar was telling you about in order to keep going 'round.
Of course, I was young, and no one had taught me about gravity then, so it was possible and I wasn't afraid. If you don't understand consequences, there IS no fear..
Needless to say, now that I am "old", I can barely swing high enough to get my feet completely off the ground without feeling my stomach drop out...
-sunny10
Posted by Susan47 on April 25, 2005, at 12:36:19
In reply to Re: Well, come join me on the swings then... » alexandra_k, posted by Larry Hoover on April 24, 2005, at 22:33:32
Ah, yes, well my brain only got a fraction of that, the teeniest little fraction, you know, but I remember the free-fall down and the sudden jerk.. that was really frightening.
Posted by Susan47 on April 25, 2005, at 12:38:04
In reply to Re: Well, come join me on the swings then... » Larry Hoover, posted by alexandra_k on April 24, 2005, at 22:42:30
EVEN MORE???? omigod, omigod, I'm sure to this day I deformed myself.
Posted by Susan47 on April 25, 2005, at 12:40:02
In reply to Re: Susan's Dumb-*ss guess » Susan47, posted by alexandra_k on April 24, 2005, at 22:44:47
I was thinking about why I retreated like that, and realized I do that all the time IRL. Having a good time, with others, then bang, the sudden need to shut it all out. But I haven't always been like that. would like to get back to the way it was, you know, endless play. I don't like my serious bent.
Posted by Susan47 on April 25, 2005, at 12:41:33
In reply to How did I miss cow tipping?, posted by gardenergirl on April 25, 2005, at 6:48:55
How do you do it, what happens, and how do the cows get back up? They can't, can they?
Posted by Susan47 on April 25, 2005, at 12:42:48
In reply to Re: Well, come join me on the swings then..., posted by sunny10 on April 25, 2005, at 9:03:53
That is scary. I have never ever seen anyone do that. If I'd seen you do that as a child, I would've freaked right out.
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Dr. Bob is Robert Hsiung, MD,
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