Torque and Turns

The Torque and Turns of Dance

By: Courtney Caccia        AP Physics Mechanics C: Period C

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Being a dancer for 15 years now, I have spent a lot of time perfecting my turns.  In dance, turns are something that often come easier to some than others.  When I realized there was actually quite a bit of physics behind the turns of dance, I became very interested.  I began to research the information about the torque in turning.  

I came across a very interesting article from Duke University school of Engineering.  The article was written by Ashley Yeager and titled Torque, Tension, Turns.  As the article clearly stated, most dancers are not knowledgable of the physics behind their turning and even if they are they are not putting the two pieces together.  To try and see how the two pieces come together, a slight experiment was conducted to observe some ballerinas.  

The article states about this experiment:

"One of her first experiments was on turns. As two of the ballerinas began to spin, their arms flowed in and out, their legs flexed and extended and their eyes focused at a point on the wall, leaving that spot only long enough for the women to whip their heads around and return their eyes to the same place.

Wisdom explained that their legs, arms and head are oscillating as they turn – moving back and forth in seemingly separate patterns. However, to be "on” in turns, she continued, “Everything really must move at the same rhythm."

Engineering systems with many parts that oscillate in rhythm are capable of highly energy-efficient fluctuations, a physical phenomenon called resonance. Wisdom asked the ballerinas to try their turns again, this time focusing on syncing their movements to create a sort of “resonance” among the oscillations of their arms, legs and heads," (Yeager). 

The article really captures the idea behind how turning works with physics and introduces this great video:

The video very well explains what the physics behind turning is all about and how it needs to be executed.  It is understood that torque is produced by the friction you push down with on the floor in a turn.  The harder you push on the floor, will result in the speed of the spin as well as the extension and retraction of the leg in a turn is going to affect the rotational inertia of the turn.  When the leg is extended you will slow down and then it is connected you will go faster.  

It was very interesting to learn about the torque behind dance and I am definitely going to be thinking about this when I am at dance working on turns!

Sources:

https://www.livestrong.com/article/507653-physics-dance-movements/

https://pratt.duke.edu/about/news/torque-tension-turns