Have an object height about four times the length standing on a floor or a table. Push quickly horizontally towards a lowest part of the object. A pushing force accelerates the object and falls it backwards. Push slowly accelerating the object to a velocity and then suddenly stop to push falls the object forward. Acceleration has produced towards the balance point of the object the force which falls the object. Force is produced because a mass is slow to obey any changes in velocity.

Fix a string at the lowest part of the object and pull it horizontally enough accelerating or suddenly stop to pull at a velocity the object falls. Pulling carefully maintaining an acceleration the object goes on its back edge the front edge off the floor and carefully slowing down the pull to maintain a deceleration goes the object on its front edge the back edge off the floor moments on balance (mgs=mah). Carefully pulling(or pushing) on count one and slowing down the pull on count two the object swings from the edge to the another while going.

SQQ. Are you saying that if I roll a marble along a table with minimal force it will just roll over the edge of the table. If we send the marble with more speed it will not just drop off the edge of the table but will travell in space. If this is so I can see that with swing this pivotal point will travell and not stand still as it will in dancing where there is a verticle lowering on some steps.

"SQQ. Are you saying that if I roll a marble along a table with minimal force it will just roll over the edge of the table. If we send the marble with more speed it will not just drop off the edge of the table but will travell in space."

Yes, but this is an example of a ballistic movement, not a swinging movement. A ballistic movement has no further input of force once it is set on its way. A swinging movement requires a force acting towards the center of the swing.

"If this is so I can see that with swing this pivotal point will travell and not stand still as it will in dancing where there is a verticle lowering on some steps."

The pivot point does not travel during a swing, but each swing may have a new pivot point. Think of Tarzan swinging on a vine from one tree, until he can grab a vine on the next tree, and so on. Only one vine per swing. Of course in dancing the center force is our feet lifting us against gravity rather than a vine hanging from above.

muy estimados señores: soy profesor de tango y bailarin profesional de este baile, me interesa los precios del curso de salsa y si cha cha cuesta igual? lo kiero de envio a lima peru por favor,, diganme los dvs comprender LEVEL I - LEVEL II - LEVEL III? un abrazo espero sus prontas respuestas

washington pinedo

Hi,
If you can have someone translate this in English,perhaps I can help you.I have an idea on what you're asking but I want to make sure and I can not answer your questions in Spanish.

Anonymous. Just as a matter of interest
and from somebody who knows nothing about physics. Are you saying that the swing of a pendulum will reach its maximum to our left. Whilst it's out there the pivotal point moves over the maximum swing of the pendulum to be repeated. In the Waltz it is one swing or two. It must be one. And whilst we are swinging before the pivotal point arrives, we have sway. The book though says we have sway on step two and three. Which I believe gives us swing on two. So trying to make sense out of three steps. At the end of one we must have a gathering of weight over the right foot to swing to the side with our left. One swing now to take our pivotal point over our left, but not quite because of the sway.. Que Serra.

"Anonymous. Just as a matter of interest
and from somebody who knows nothing about physics. Are you saying that the swing of a pendulum will reach its maximum to our left. Whilst it's out there the pivotal point moves over the maximum swing of the pendulum to be repeated. In the Waltz it is one swing or two. It must be one."

Each time you reach a maximum of rise and start downwards, you begin a new swing, which will consist of the down and the following up. When you reach the maxmimum of rise and start down again, that will now be a new swing.

For waltz pendulum swing, each swing has a single fixed point about which it occurs. (At least in terms of the location of that point over the floor area, it's altitude might vary)

"And whilst we are swinging before the pivotal point arrives, we have sway."

You shouldn't. First, its probably not a good idea to try to literally connect sway and swing, because that will lead you to seeing the sway as being related to a pendulum swing, which it really is not.

But to correct the specific mistake - before you pass the pivot point of the swing, you are dancing the downswing. And downswings do not really have sway, except maybe a tiny bit right at the beginning which rapdily vanishes. Only the upswing - occuring after you pass under the pivot point of the swing - would have lasting sway.

"The book though says we have sway on step two and three."

The sway develops throughout step two, it is there at the beginning of step three but should usually vanish during step three so that there is none at the end.

"Which I believe gives us swing on two."

You have swing on three, one, and two. Then a new swing on the next three, one, two.

Imagine "dancing" with a small child you are pushing in a playground swing (though you would have to reverse direction on each peak of rise and go back the way you came)

If you want to understand swing, think of your body as a cannon ball (located at your center) on a string. Swing is about the path of your body center, not the shape or alignment or orientation of your body (those are important, but they are largely seperate concepts)

If you want to understand sway, think of dancing into the wind of your movement, and what that wind (if it were strong enough) would do to your shape. Not a great model, but maybe a start.

Anonymous. I think this belongs in the Physics of a Step. To go to the point of imbalance and to then catch the weight. To me that means that if I stand with my feet together and lean forward untill my weight is no longer balance. If I don't move my foot and catch my weight I will fall flat on my face. That is Latin and not in the Standard style of dancing. With a good Latin teacher who knows how to teach, we learn this the first time we ever do a Rumba Walk. To put this into Modern. I have never heard of it. I have enough DVD's of both styles of dancing which I have looked at in slow motion. In Standard there is no visible signes of an imbalanced weight. In Latin there is. But even in Latin the foot always arrives first every time and will beat the body.

You can be off balance having your body straight upward. It can be demonstrated by leaning flat towards a wall standing on the ball of a foot that is on a distance of about 0,35 m from the wall the whole body touching the wall from the nose to the knee of the moving foot.

Leaning on your back foot flat towards the wall you feel how much force acceleration must produce towards you to balance moments to carry your weight not to fall too early on the moving foot. Bending your back backwards also balances the moments moving the balance point of the body nearer above the ball of the standing foot.