Physics In Ballroom Dancing: Energy And Motion.
Guest Writer: Prof. Dr. Dierck-Ekkehard Liebscher
Editing And Translation: Kerstin Lange
Portrait Prof. Dr. Liebscher: Courtesy Prof. Dr. Liebscher
Others / processing: Helmut Römhild
means something different from the energies which we feel, which flow through our bodies, which we can unleash. It’s a quantity which can be
objectively measured in watt per second or kilowatt per hour.
A state of stability means that the energy’s value can no longer be reduced: the system can only absorb energy from outside
but not release any.
Only energy can bring a system’s state from
balance to instability.
If instability means motion, the input of energy has to be combined with an impulse, in other words with force.
Prof. Dr. sc. nat.
More at www.aip.de
A human being is a rather instable system.
It has to be in order to be able to move on its own accord
The centre of gravity, located about 90 cm higher than its lowest possible position, is the means to transform potential energy into kinetic energy, the energy of motion.
Potential energy increase is linear in relation to the height above ground level (valid for systems in the field of gravity close
the earth’s surface). Kinetic energy (energy of motion) increases with the square of the speed.
Lowering the centre of gravity by 10 cm provides sufficient kinetic energy (1 J per kilogram bodymass) to accelerate from zero to a velocity of 140 cm per second.
Force has to be added but only as much as is necessary to change the centre of gravity’s downward direction into a forward motion.
If the body’s muscles were simply springs applying force would not alter the balance of energy.
But since muscles are something different, chemically bound energy inside the muscles has to be made available.
This is only a minor transction – the dominant portion of kinectic energy results from lowering the centre of gravity.
... moving without effort.
To demonstrate what it means to move without effort, without applying major force to initialize movements, the Viennese Waltz provides the best example.
With a little exaggeration one can say that a dancer dancing the Viennese Waltz doesn’t have to make turns – the dancer is turned. Of course I am talking about the Right Turn, also called Natural Turn for that specific reason.
There is just one continous forward movement.
Since the dancers face each other they must not dance backwards, not initialize the backward movement which would
break the posture. Never dance backwards, dancing backwards means to be danced backwards.
The initiative is always with the dancer moving forward.
Just overtaking the partner – which stands to the right – on the left side results in a right turn.
Think of a river running faster in the middle of the stream, slower close to the sides: leaves on the water always start to spin when they reach the riverside.
Stepping backwards means to be moved backwards, guided into the backward step, by the forward motion of the partner.
After each beat it’s the other partner’s turn to take the initiative and to move forward. The result: a simple, effortless dialogue.
If one feels the need to count the beat, it shouldn’t be “one two three one two three” but “now you, now me, now you, now me”.
Even the Reverse Turn is based on the partners overtaking each other.
But now the lady is on the ‘wrong’ side and the gentleman can no longer make the lady let him pass.
The gentleman can lead the Right Turn but not the Reverse Turn: He would break the posture.
In one of his You-Tube videos Marcus Hilton makes the point that a gentleman can only invite the lady to dance the Reverse Turn .
But it’s up to the lady to execute the move in order to maintain the posture.
From the gentleman’s point of view the Reverse Turn is not effortless: he has to persuade his partner.
All this is based on physical laws which we simply have to obey.
The course of nature has of course to be accompanied by skill and style, the dancer’s task is to accquire the necessary techniques and be able to control footwork, angles of turns, extension and poise etc.
©: Ballroom Website, 2010