The Motion of Ballet Rotations

While trained dancers may appear effortlessly coordinated on stage, there is an extraordinary level of skill, training, practice and science necessary for a successful performance. Two dancers from the Iowa State University 4-H Youth Development Nutcracker + STEM performance demonstrate just a few of the movements they used in the performance and the physical science concepts they must consider as they dance. As dancers push off the ground to initiate a spin, the ground gives enough reaction force to enable the turn.

As dancers pull in their arms and legs closer to the body they decrease the moment of inertia which allows speed to increase. Similarly, as dancers extend their arms and legs away from their body they increase moment of inertia which causes speed to decrease.

By changing the shape of your body (ex: arms or legs), you can increase or decrease your rotation speed.

Video

Ames

Iowa Core Standard

MS-PS1-1

Develop models to describe the atomic composition of simple molecules and extended structures.

Driving Question

How do forces impact a dancer in motion?

Probing Questions

What forces must a dancer consider when moving?
What do you notice about how fast they are spinning?
Does their speed change as they move their arms or legs?
How do you think they could spin faster?

Classroom Suggestions

Students could:

Complete the Iowa State University 4-H Nutcracker + STEM “Nutcracker Choreography Challenge” to explore some of the ways dancers try to increase and decrease these forces.
Trying to spin, or pirouette, the way the dancers did. Ask them to think about the position of their arms and legs during these movements.
Use a PocketLab or similar sensor to graph the movements of a pirouette or spinning in a chair.

Resources

Iowa State University | 4-H Nutcracker + STEM: Nutcracker Choreography Challenge: This document allows students to explore some of the ways dancers try to increase and decrease these forces.
The Science of Falling | How Dancers Spin Without Getting Dizzy: The Science Behind Their Control and Balance: This article describes the physiological science behind dancers' movements.
The Lewis Foundation of Classical Ballet | Where Art Meets Science: The Physics Behind Ballet: This article describes the forces and laws that make ballet performances possible.

Contributors

Media produced by Iowa PBS in partnership with Iowa 4-H Youth Development and Stephens Auditorium.