full transcript
From the Ted Talk by Arleen Sugano: The physics of the "hardest move" in ballet
Unscramble the Blue Letters
The other option is for the dancer to bring her arms or leg in closer to her body once she returns to pointe. Why does this work? Like every other turn in ballet, the fouetté is gnorveed by angular momentum, which is equal to the dancer's angular velocity times her rotational inertia. And except for what's lost to friction, that angular momentum has to stay constant while the dncaer is on pointe. That's called covsriaotenn of angluar momentum. Now, rotational inertia can be thought of as a body's resistance to rotational motion. It increases when more mass is distributed further from the axis of rotation, and decarsees when the mass is distributed closer to the axis of rotation. So as she brings her arms closer to her body, her rotational inertia shrinks. In oredr to conserve angular momentum, her angular velocity, the speed of her turn, has to increase, allowing the same amount of setrod moenmtum to crary her through multiple turns. You've probably seen ice skaters do the same thing, snnipnig faster and faster by drawing in their arms and legs.
Open Cloze
The other option is for the dancer to bring her arms or leg in closer to her body once she returns to pointe. Why does this work? Like every other turn in ballet, the fouetté is ________ by angular momentum, which is equal to the dancer's angular velocity times her rotational inertia. And except for what's lost to friction, that angular momentum has to stay constant while the ______ is on pointe. That's called ____________ of _______ momentum. Now, rotational inertia can be thought of as a body's resistance to rotational motion. It increases when more mass is distributed further from the axis of rotation, and _________ when the mass is distributed closer to the axis of rotation. So as she brings her arms closer to her body, her rotational inertia shrinks. In _____ to conserve angular momentum, her angular velocity, the speed of her turn, has to increase, allowing the same amount of ______ ________ to _____ her through multiple turns. You've probably seen ice skaters do the same thing, ________ faster and faster by drawing in their arms and legs.
Solution
- momentum
- dancer
- conservation
- stored
- order
- spinning
- angular
- governed
- decreases
- carry
Original Text
The other option is for the dancer to bring her arms or leg in closer to her body once she returns to pointe. Why does this work? Like every other turn in ballet, the fouetté is governed by angular momentum, which is equal to the dancer's angular velocity times her rotational inertia. And except for what's lost to friction, that angular momentum has to stay constant while the dancer is on pointe. That's called conservation of angular momentum. Now, rotational inertia can be thought of as a body's resistance to rotational motion. It increases when more mass is distributed further from the axis of rotation, and decreases when the mass is distributed closer to the axis of rotation. So as she brings her arms closer to her body, her rotational inertia shrinks. In order to conserve angular momentum, her angular velocity, the speed of her turn, has to increase, allowing the same amount of stored momentum to carry her through multiple turns. You've probably seen ice skaters do the same thing, spinning faster and faster by drawing in their arms and legs.
Frequently Occurring Word Combinations
ngrams of length 2
collocation |
frequency |
angular momentum |
3 |
rotational inertia |
3 |
black swan |
2 |
stored momentum |
2 |
Important Words
- allowing
- amount
- angular
- arms
- axis
- ballet
- body
- bring
- brings
- called
- carry
- closer
- conservation
- conserve
- constant
- dancer
- decreases
- distributed
- drawing
- equal
- faster
- fouetté
- friction
- governed
- ice
- increase
- increases
- inertia
- leg
- legs
- lost
- mass
- momentum
- motion
- multiple
- option
- order
- pointe
- resistance
- returns
- rotation
- rotational
- shrinks
- skaters
- speed
- spinning
- stay
- stored
- thought
- times
- turn
- turns
- velocity
- work