Leading: When does a push become a shove

[El Salsero Gringo]

Don't worry - normal service is resumed...
I think you'll find DavidB is quite aware of the physical equations involved...

Pleased to hear it

Do you really mean this?

Absolutely I do. I provide a force through my/our hands. If the follower allows that hand to move towards her then a force acts through a distance and energy transfers. If she doesn't allow the hand to move - by maintaining an equal and opposite force - then the force acts through no distance and no energy transfer occurs (like the wall) - GCSE physics that I know you understand well enough too.

You seem to be implying that you provide all the force required for the follow's movement, and it's up to her how much to resist.

I don't know how you come up with this interpretation of what I said, so I need go no further except to say that I agree that it's a load of rubbish.

When I push harder on the accelerator of the car, it doesn't mean I'm providing the energy to make it go faster.

True. I think a better analogy (if we're talking cars) is power steering. The servo mechanism acts as a true amplifier. If it's faulty, you get no steering at all when you turn the wheel (spaghetti arms) or not enough amplification (no hydraulic pressure, perhaps). But you turn the wheel regardless, and it's up the mechanism itself as to how much energy you have to put in and how much it provides.

[El Salsero Gringo]

Do you really mean this? You seem to be implying that you provide all the force required for the follow's movement, and it's up to her how much to resist.

Look, isuppose I lead a step back by pushing the lady away with the back of my hand. She reacts against me by providing an equal force in her arm muscle which in turn is sufficient to generate the backwards acceleration of the rest of her body (the step back) before it brakes against the friction of the rear foot landing on the floor. Our hands stay perfectly still so no energy is transferred between them. But it's nonsense to ask "who" provides the force - we both do.

If you look at, say, a whip in WCS

Leading a whip as far as I can tell uses the same kind of technique to leverage a lady's momentum to change her direction (energetically speaking, for free) without changing her speed (energetically costly) that Judo uses to throw someone.

If I want to dance with a shopping trolley, I'll push it up to speed (hard), then I can swing it about in arcs (just brake one of the wheels) or make it spin (very easy).

[David Franklin]

I don't know how you come up with this interpretation of what I said, so I need go no further except to say that I agree that it's a load of rubbish.

Basically because you seem to be disagreeing with DavidB's comment that the force/energy[*] comes from the lady's legs.

Pretty much every other part of the argument comes from the consequences of that. You've given other examples, analogies etc., but none of them are really compatible with what you disagreed with initially. (I think the most obvious problem is that if the force doesn't come from the lady's legs, you would be able to lead it the same way if she were in a wheelchair/wearing frictionless soles etc. And you can't).

[*] And I don't see why you think there's a significant distinction here - she supplies force that is used to change her momentum and hence her kinetic energy. We can play all kinds of games about what what the exact integrals over time etc. but it's all the same thing really.

[Gojive]

If I want to dance with a shopping trolley, I'll push it up to speed (hard), then I can swing it about in arcs (just brake one of the wheels) or make it spin (very easy).

I can lead a basket quite well

Sorry - couldn't 'resist'....I think I'd better checkout of this thread now...

[El Salsero Gringo]

Basically because you seem to be disagreeing with DavidB's comment that the force/energy[*] comes from the lady's legs.

for a simple step back, most of the force does come through the hands. Try leading yourself into a step back with your hand against the wall - it's very easy. Most of the backwards push comes through your arm. You can do it standing on one foot for instance - at least until you have to put the back foot down to brake you.

[*]And I don't see why you think there's a significant distinction here.

The distinction is crucial, because providing the "push" is not the same as "doing the work". You can provide more or less push, but the follower is still moving themselves.

[TheTramp]

But the question here is when does a push become a shove?

Are you regretting this question yet?

It all seemed soooo innocent. As a newcomer, you just didn't know what to expect.

Whatever you do, please don't get onto such threads as:

"Should the man actually move his feet when leading"
"What are acceptable ethics in opening up your own dance class"

And definitely not:

"Should smoking be allowed near the dance floor"

(Just a mild warning!)

[David Franklin]

For normal vertical dancing (ie no drops, leans or aerials) then the force comes from the lady's legs, not the mans arms.

Not always.

providing the "push" is not the same as "doing the work". You can provide more or less push, but the follower is still moving themselves.

This is now completely nonsensical to me. I think I can make sense of it by some very convoluted arguments about what you count as push, force, etc., but I don't see the point.

As far as the whip is concerned, a WCS whip does involve dissipation of energy (as it's slotted). But that is beside the point - the force required to change the momentum is significant even in a circular whip. And just because force is applied in a direction orthogonal to movement and therefore doesn't cause energy transfer doesn't mean it won't be felt. Our 'signature move' is pretty much a textbook example of this - about 100kg of tension in order to spin the follow about a fixed point. And it feels brutal, to be honest.

[El Salsero Gringo]

... but I don't see the point.

That just about wraps it up then.

[Ghost]

ESG - a few questions?

Do you know the four corner drop from aikido?

Would it be fair to say that the amount of force in your lead varies depending upon what you want to do?

Would it be fair to say that in some instances once you've got the lady up to speed, you're then actually using very light adjustments?

Would it be fair to say that the overal force between you is very small

Would it be fair to say that the lady's balance and momentum is very important in your style of dance - you're not so much physically manhandling her as slightly disrupting her balance in order to cause her to move / keep moving / change direction (hence the four corner drop question)?

I like Foxy Lady's answer. Different ways of approaching leading. It sounds like the ladies who want a firmer lead prefer your (ESG's) approach

(As always I could be wrong)

Christopher

[David Franklin]

I like Foxy Lady's answer. Different ways of approaching leading. It sounds like the ladies who want a firmer lead prefer your (ESG's) approach

Have to disagree here, on the basis that the argument is more about ESG's analysis than his approach. In other words, I believe that even with a very firm lead, the follow is providing the vast majority of the energy. (And I think tend towards the firmer end of the leading spectrum myself).

As far as shopping trolley discussions go, I've suddenly remembered a trip to B&Q with Will, where we had a trolley loaded to approximately 100kg. And it took both of us to manouveur it and we certainly couldn't change direction quickly. Whereas I've lead ladies that heavy using only a couple of fingers.

[Ghost]

Have to disagree here, on the basis that the argument is more about ESG's analysis than his approach.
(Snip gOod stuff)

If I had any sense I'd wait for ESG's reply but as I'm going out soon anyway.....

His push against a wall example only works because of balance. Try this. Stand facing the wall a foot away and push off with one outstretched arm. You should fall back easily. Now face sideways to the wall and repeat. You won't move. So technically it's gravity that's supplying the energy. Which comes through your legs - which goes back to what DavidB said in the first place. No energy in the lady's legs and she'll just collapse.

But I might have misunderstood

Be Well,
Christopher

[MartinHarper]

Kevin + Carla, Bei Mir Bist Du Schoen, video's been linked before:
http://video.google.com/videoplay?do...in+carla+lindy

There's a nice little move that's done at both 1m10 and 2m50, which seems to be a decent illustration of ESG's point about redirecting momentum. One thing I noticed is that Carla is controlling her own moment of inertia in order to make that redirection very easy. By contrast, a loaded shopping trolley has a large and fixed moment of inertia, and so is harder to dance with.

[Saxylady]

By contrast, a loaded shopping trolley ...is harder to dance with.

than all ladies - or just Carla??

[David Franklin]

Kevin + Carla, Bei Mir Bist Du Schoen, video's been linked before:
http://video.google.com/videoplay?do...in+carla+lindy

There's a nice little move that's done at both 1m10 and 2m50

I'm having lots of trouble with the google player, so I can only get about 1 second of play at a time, but the two moves I'm seeing at 1m10 and 2m50 aren't terribly similar, so I can't really see what you mean. As a general comment, I think Lindy isn't a great dance to take examples from - there are many Lindy scenarios where the lead does have to provide significant force, while such scenarios are exceedingly rare in MJ or WCS outside of leveraged moves. (The other exception I find in MJ is that involved in rapid 'paired turns' like pivot turns or penguin walks).

which seems to be a decent illustration of ESG's point about redirecting momentum.

There's nothing "magic" about redirecting momentum. In other words, you can't say "it would be exceedingly painful to apply enough force to stop someone moving at 10m/s in one direction and send her back the same way in 2 beats, but because I just redirected her momentum it's OK". You cannot redirect momentum without applying a force. It's almost a definition: force = rate of change of momentum. You may do no work in applying that force (as is the case in an idealised Lindy whip), but that's a different question. I suspect you actually apply a higher average force doing a Lindy type whip than a WCS whip (in the case of an idealised Lindy whip I think the average force is PI/2 times that in an idealised WCS one). As for redirection being easy, as I said before, we do possibly the "ultimate" momentum redirection move (continuous floorsweep), and the tension required is about 100kg!

One thing I noticed is that Carla is controlling her own moment of inertia in order to make that redirection very easy. By contrast, a loaded shopping trolley has a large and fixed moment of inertia, and so is harder to dance with.

It's hard to know what you're talking about given I can't identify the move reliably, but I would be surprised if the moment of inertia of Carla (as opposed to the Kevin/Carla system) was significant on a whip-like move (as opposed to a spin).

[LMC]

@ technical stuff

I know very well that my following is lighter if I've been dancing with more 'advanced' dancers, and tends to be a bit "heavy" if I'm just off taxi duty.

For the first move - I personally prefer more of a 'pull' on the hip than a 'push' with the hand (whether I'm following or leading a first move). Other followers may well differ.

For a sway - IMO, the lead needs to be fairly 'firm' for this, to make sure that the follower actually twists in - otherwise they will just step forward.

For spinning - I'll spin how many times I damn well want to*, however much 'strength' has been put into the lead.

*usually once. Spinning is not my strong point

I expect matching tension has already been mentioned somewhere in amongst all the PhD stuff in this thread that has gone straight over my head. In theory, the follower should match the leader's tension. In practice, if the lead is *too* strong then this gets silly (and painful!). So, when faced with too firm a lead, I tend to try reducing my tension first - which frequently works by getting the leader to match me (if it don't work, then I ask them to be more gentle with me!).

To any halfway decent follower (even to those who, like me, are still aspiring to that level) clarity, confidence and direction of the lead should be far more important than its physical strength. Ditto 'flow' (what timbp said) - stop/start is far more difficult (and potentially annoying, if not painful) to follow than a smooth lead. "Noise" in the form of a bouncy hand makes the lead far more difficult to translate, which I suspect is why (in my experience anyway) hand bouncers often tend also to be yankers...

I would agree that more 'internal' tension is needed on a double time move - I'm not sure that the lead necessarily needs to be more forceful, but then I can barely follow double time moves, let alone lead 'em

The short answer to the original question is probably that it's the same as asking how long is a piece of string...

[Ghost]

I know very well that my following is lighter if I've been dancing with more 'advanced' dancers, and tends to be a bit "heavy" if I'm just off taxi duty.

(snip good stuff)

I think of this like talking to someone who's just come out of a loud Rock Concert - you need to shout at them for a bit . It stops them having to keep saying "Pardon?".

For spinning - I'll spin how many times I damn well want to*, however much 'strength' has been put into the lead.

Reflecting on this a bit more; I prefer to follow in a state of "I'm a leaf on the wind" - but that's me. If a lady wants to follow in a state of more internal tension " I am woman hear me roar!", then she needs the lead to match that in order for it to work. Maybe?

Be Well,
Christopher

[Merovingian]

Are you regretting this question yet?

It all seemed soooo innocent. As a newcomer, you just didn't know what to expect.

Whatever you do, please don't get onto such threads as:

"Should the man actually move his feet when leading"
"What are acceptable ethics in opening up your own dance class"

And definitely not:

"Should smoking be allowed near the dance floor"

(Just a mild warning!)

Thanks for the warning !

... fascinating information here actually. I think the problem with these kind of questions is that there is no straight answer, I was expecting something along the lines of what Ghost <a href="http://www.cerocscotland.com/forum/showthread.php?t=8652#2">*</A> && Gadget <a href="http://www.cerocscotland.com/forum/showthread.php?t=8652#13">*</a> mentioned, and some suggestions.

(There is just so much useful info here that I can't thank each one individually, I'm already glad that I came across this forum)

And I've filed away all this technical theory for a review about 3 months from now, when I have a better lead and more experiance

Though I would try and stay away from jounces ( for now )

[Keith J]

Good Q!, lets see if this helps...
Firstly, it possibly depends on the ladies experience and yours as a lead, and measuring the required response. Let me add 'it ain't necessarily so' that the turn out is required as many advanced ladies may steal the exit to play with 'styling'. The intent and lead is gone at that juncture.

The etiquette suggests one gives a signal, if its not followed never ever persist, (this being a no pain experience). Allow what happens to occur you may be surprised at some pleasing results and learn something as well.

[LMC]

It's no good... I can't resist (Trampy, your list was missing one )

KeithJ, what do you mean by a signal?

[El Salsero Gringo]

If I had any sense I'd wait for ESG's reply but as I'm going out soon anyway.....

{snip}

No energy in the lady's legs and she'll just collapse.

But I might have misunderstood

You've misunderstood (or we're talking at cross purposes) what I (it maybe me alone, perhaps) mean when I say energy. There's no "energy change" involved in standing stationary on the floor - my desk does it 24/7 with no source of power - so does the building I'm sitting in, and Mount Everest too. There's biological 'energy' involved in keeping muscles tense, but that (mis)use of the word energy doesn't get you very far in analysing the physics of dance.

(by the way - David F - naughty - supplying tensions in Kg - which is a measurement of mass...)