A question on spinning

[Dorothy]

I am trying to keep my legs together whilst I spin, lookd dead nice. Also keepng frame upright and not leaning forward. With regards to multiple, I can at best get 1 and a 1/2. Men often puch me off balance too, or is that my fault?

[David Franklin]

When you consider the relative forces involved (I vaguely recall someone clever saying this beforehand - I think it was either DavidB or DavidF), it's impossible for a leader to contribute much of the energy to actually spin someone - all they can do is vary the strength of the signal to the follower to use as invitation.

If it was the fairly technical post about the physics involved in leading and the forces required, then I think it was me. But then I actually said that spinning is the one potential exception - relatively speaking, it doesn't take that much force to spin someone.

I must admit I haven't really got my head around the mathematics of "power-leading" a spin without taking a follow off balance. If you're only using one point of contact, it seems to me that any force you provide is inherently going to take the follow off balance. The only analysis I've seen is for turns 'on pointe' in ballet(*), where the author shows that an additional torque is required that is provided by the dancers using a clasped grip that allows the lead to apply force by 'twisting' the grip. That is clearly not applicable to free spins in MJ, however.

In practical terms the main thing I do is try to make the lead last longer rather than harder. The same force will provide double the angular momentum if you can sustain it for twice as long.

(*) Physics and the Art of Dance by Kenneth Laws.

[happygoldfish]

I must admit I haven't really got my head around the mathematics of "power-leading" a spin without taking a follow off balance. If you're only using one point of contact, it seems to me that any force you provide is inherently going to take the follow off balance.

Yes, you're referring to the obvious fact that the only point of contact between the partners (the follower's hand) is about 4 feet above the fixed pivot point (the follower's feet), and so produces a falling-over-backward torque.

Let's see …

The force on her hand is usually at an angle towards the floor — let's call the horizontal component H, northward, and the vertical component V, downward.

The force on her centre of gravity (strictly, it acts on every part of her body, but the average always goes through the c. of g., by definition) is simply her weight, W.

The force from the floor will have two components: a vertical one equal to W + V, upward, and a horizontal one equal to H, southward (unless H is really large, in which case the follower's feet will slide).

(There will also be a horizontal-plane "spinny" friction, and some air resistance, but let's ignore that.)

Two forces whose lines (as in this case) do not meet combine to produce a turning force (or torque).

So the two horizontal forces of strength H, north and south, produce a falling-over-northward torque (spinning about an East-West line through the follower's feet) of strength 2Hh, where h is the height of the follower's hand.

Once the follower starts a falling-over-northward turn, if her hand is no longer in contact with the leader's hand, no amount of wiggling will enable her to stop that falling-over-northward without making a step northward. So the follower must ensure that, by the time the leader lets go, her falling-over-northward turn is zero.

So she must cancel it by using her body weight (much like one subconsciously does when turning on a bicycle).

She does this by leaning slightly southwards (she probably isn't aware she's doing it, much as on a bicycle). If her centre of gravity is now a horizontal distance d in front of her feet, then the falling-over-southward torque equals (2W+V)d.

H is a lot less than W (if it wasn't, then the follower's feet would slide), though V could theoretically be as much as the leader's weight.

If the angle of push is 45°, say, then V = H. If it is steeper, at 60°, then V = 1.7H.

The spinning force (about the follower's vertical axis) depends only on H.

For falling-over-northward balance, she needs 2Hh = (2W+V)d, or …

d/h = H/(W + V/2).

So if, say, H = W/20 and V = H, then d is about 2 inches (by comparison, the difference between weight-over-the-heel and weight-over-the-ball is about 6 inches).

The leader should (probably usually doesn't!) instinctively feel when this balance has been reached, and let go at that point.

Of course, some followers lean backward rather than forward, and so spend the whole turn slowly falling-over-northward, and so have to step back before the turn is finished. But a balanced follower will finish the turn on balance, and can step back at her leisure.

Do any teachers out there have instruments which could measure typical values of H?

btw, why should the man push diagonally downward, and not horizontally (so V = 0)? An increase in V seems to make very little difference to the follower's required forward-lean, d.

I think it's solely because it uses different shoulder muscles, and so is more comfortable for the follower. Lean against a wall with one hand, about shoulder height, supporting a lot of your weight. Try pushing downward against the wall as you lean — it's uncomfortable at the shoulder. The most comfortable angle seems to be to push diagonally upward, corresponding to the wall (or the leader) pushing diagonally downward on you.

… relatively speaking, it doesn't take that much force to spin someone.

The horizontal force, H, can be very small, and still give a good spin.

[Jamie]

{snip stuff about the theory of spinning...}

Ok, I'll admit it, double you - tee - eff? So in english all that means?

As we're all trying to be clever using theorys... I've extensively tried using different methods of spinning, infact I dedicated 6 months solid to nothing but learning how to spin.. I might not know the physics behind it, but I do know that put simply, the greater the tension in the leaders arm and force used to spin produces a longer spin.. If someone simply taps me on my forearm, I'll probably spin once or not at all..

I might not know the theory it, but I'll gladly demonstrate it in person

Besides... if I were to spin loads of times (using my own propulsion) then I wouldn't really be following? I'd have to anticipate the spin in order to throw myself round? That's what I was told on this forum about 6 months ago... Or has that idea gone out the window now?

[David Franklin]

Yes, you're referring to the obvious fact that the only point of contact between the partners (the follower's hand) is about 4 feet above the fixed pivot point (the follower's feet), and so produces a falling-over-backward torque.

~snip~

She does this by leaning slightly southwards (she probably isn't aware she's doing it, much as on a bicycle). If her centre of gravity is now a horizontal distance d in front of her feet, then the falling-over-southward torque equals (2W+V)d.

But surely at this point the follow is off balance - in the sense that she is relying on force from the lead to stay balanced. There's an obvious problem there for when the lead lets go.

But I think a bigger problem with this analysis is that it's a static one, while you really need to considering the stability of the system. In practical terms, the problem is that for a follow spinning (on a much smaller surface than the entire flat of one foot) the system is really not very stable at all.

This is then exacerbated by the problem that most people find the dynamic adjustments needed to maintain balance when spinning to be totally counter-intuitive. Basically, they tend to make things worse, rather than better.

There's actually a fair amount of evidence that really good spinners are just far far better than the average when it comes to correcting for being off balance. You can force them off balance during the spin (by pushing them) and they can correct for it. Whereas an "average" spinner is generally doomed once they move a little off axis.

A corollary of this is that preps that work for a great spinner are probably not suitable for the typical dancer.

[Daisy Chain]

Compleatly disagree with that. You push someone hard enough and they will turn faster and make it harder for them to stop in one turn. Surley.

NOOOOOOOOOOOOOOOO! The harder you push, the more likely you are to send the follower off-balance (making it difficult to perform even 1 spin without falling out of it part way round)

It's the quality (not the quantity) of the push that matters. It is perfectly possible to execute beautiful multiple spins from a non-forceful but balanced push.

Daisy

(A Horrified Little Flower)

[Andy McGregor]

Ah, here's the post I was thinking of:


As always, David expresses it much better than I could.

David B expresses it so much better than I could too

Woodface is on my ignore list so I have the joy of not knowing what he posted unless somebody quotes him. In a thread about spinning woodface will comment as if he knows more than everyone else - whilst ignoring or criticising the likes of David B, David Franklin and everyone else called David. When reading this you must remember that the two listed David's are many-times national champion dancers and that woodface has one medal and that is for Double-Trouble from Ceroc - Double Trouble is not especially serious and Ceroc is not an independent national body looking for the best dancers in the country: Ceroc is a franchise organisation and a business. Would you ask McDonalds to judge a hamburger making contest?

Back to the plot. At the start of this thread there is dancer who has just started MJ. She wants to know about spinning in MJ. The first thing to remember is that MJ is a social dance, it's a partnership between two people. In most circumstances you part as a couple to spin for 2 musical beats. Then you reconnect and continue the partnership. The person spinning can usually get one or two spins completed with style and precision within those 2 musical beats. Jamie is a Queen of spinning and might be able to spin more in the time To spin for more than 2 beats means that the partnership is starting to disappear and the spinner is pretty much dancing on their own while their partner becomes a spectator.

The above paragraph doesn't mean that you can never part for more than 2 beats. It is quite acceptable to part for a minor phrase of 8 beats or 2 bars. The partnership recommences at the start of the next bar. However, this really only happens when there is something like a break in the music on beat one of the first bar - the last thing you'd be doing in a break is spinning like a top.

The only place for multiple spins is showing off. It's not about your partner any more, it's about your spectators. You may wish to show off to the judges in a competition, a cabaret audience, people at the side of the floor who are taking a break, you may even be showing off to your partner, but you are no longer a partnership in the way that MJ is meant to be. This doesn't mean that multiple spinning is wrong or bad, it just means that, IMHO, it is not really part of a social dance.

[JCB]

For falling-over-northward balance, she needs 2Hh = (2W+V)d, or …

d/h = H/(W + V/2).

Excuse me, Happygoldfish, but haven't you have failed to factor in quantum mechanics? If the follower wishes strongly to be in another place at this point, the uncertainty principal would surely affect your calculations. In fact after your explanation, I think I would wish to be in several different places at the same time, (so long as none of them involved experimental revolving), and in that case it would be very difficult to determine which orbit my spin was in.

Do any teachers out there have instruments which could measure typical values of H?

Wouldn't a fish scale suffice?

[JCB]

O.K., now that I have got the silliness out of my system, I need spinning help, please!
Connie, I hope you don’t mind if I hitch a ride on your thread? , because mine is a very different problem from yours.
I did have a fairly dependable single spin. I couldn’t control the speed, and couldn’t do multiples, but I could spin on the spot, and stop, under control, and balanced. That had taken me nearly a year to achieve, because my inner ear balance is a bit wonky. (If I close my eyes while standing still, I fall over. On the plus side, I rarely got dizzy, and never have suffered from motion sickness ).
Then I got a minor earache, with a cold. Both cleared up quickly, but my spin disappeared with them!
I also get dizzy – very unpleasant!
Practising on my own, by pushing off with my foot (how I managed to improve in the first place) is disastrous. I manage a couple of spins, then the whole process deteriorates. I have searched through old spinning threads, but nothing quite applies. It has been a month now, and my assisted spins are passable, or rescue-able, but feel really unstable. But turns are fine; in fact I can manage multiple turns, with no problem.
Can any formerly rotationally-challenged forumites offer advice?

[timbp]

If the follower wishes strongly to be in another place at this point,

Then she's not following!
The follower should wish to be where the leader wants her (possibly with the caveat that this should be on the dance floor).

[JCB]

...The follower should wish to be where the leader wants her (possibly with the caveat that this should be on the dance floor).

You may well have a valid point, but although it may be rare, I suspect there are many followers on the forum who have very occasionally wished most fervently to be elsewhere, so it could colour the sample.
Besides, surely there are cases where propriety bans the follower and leader doing exactly what the leader wants on the dance floor?
In addition, there is always the problem that the act of measuring something actually changes the object being measured. ( Do you suppose this may be behind the lack of agreement on the High Street as to exactly what size a "Size 12" is?)
...

[JCB]

...Now, any advice from formerly wobbly spinners? ...

[Connie]

...Now, any advice from formerly wobbly spinners? ...

I cant give you any advice on spinning as I am useless at spinning on the "wrong" foot in ceroc. However have you ever considered training with a wobble/balance board?

I use a wobble board for core strength, balance, and so on, its really a brilliant tool to use. And if you have general problems with your balance I am sure a wobble board can help you no end. Just make sure you purchase a 12% and not 16% board.

Once you have used it for a while, you should progress to be able to balance on it on one foot, once you mastered that you can use your arms to propel you and the board into a "spin".

[JCB]

However have you ever considered training with a wobble/balance board?...<snip>... you can use your arms to propel you and the board into a "spin".

Sounds like it might be worth a try, thanks! Why is the 12° preferable to the16° board?
I have had the ear/balance problem since I was very young, and have learned to compensate quite well using visual and tactile cues. (I have even had a go at windsurfing - quite funny to watch, but a great disappointment to my kids, as I only fell in 3 times, and they weren't quick enough with the camera!)
Trying to spin a balance board sounds like a challenge - perhaps I will save that for later
Can you (or anyone ) recommend more basic exercises?

[drathzel]

build up your spins slowly going about a 1/4 at a time then working up to 1/2 then 3/4 then full spin.

Go one way once then the other way once. Sounds daft but it will help you get less dizzy!

[Connie]

Sounds like it might be worth a try, thanks! Why is the 12° preferable to the16° board?

The 12 and 16 refers to the tilt of the board, and thense how difficult it is to master it. The 16 degree board is really for intermediate to advanced users. If you have some balance problems I wouldnt recommend you to start on a board with a 16 degree tilt.

[JCB]

O.K., this is embarrassing: my spin re-appeared, all by itself, on Thursday.
I have no idea what, if anything, I did right! In fact, practising was so frustrating, I had even given that a rest.

I am definitely going to look into that wobble board, Connie. With some extra work perhaps I can master a double-spin before it disappears again!

[drathzel]

Glad you got your mo-jo back JCB! Double spins arent all that any way

[Amir]

The only place for multiple spins is showing off. It's not about your partner any more, ... This doesn't mean that multiple spinning is wrong or bad, it just means that, IMHO, it is not really part of a social dance.

I used to think this, and almost stopped doing multiple spins altogether. But then one or two times I noticed that after spinning the girl was smiling, and she wasn't before. That's when I realized dancing with someone who is doing cool things can make it more fun for you, too, as long as you are not intimidating them.

Part of the social aspect of the dance is that I am my partner's spectator and she is mine - if my partner is fun to watch it makes the dance more fun for me, adds variety, gives me ideas.

You can spin for yourself and ignore your partner or you can spin for your partner. Also, if my partner is spinning like crazy, there is a small irrational part of me that thinks I had something to do with it, and I feel proud. If it works the other way too then what's there to lose?

So if you think you can entertain your partner with a couple of spins, I would say do it. Be a spinster.

[Lee Bartholomew]

{snip}

Couldn't have put that better myself



(no really, I couldn't)