Aerial Physics: Aerial Skiing

Air Date: 12/08/2009
Source:
NBC Learn
Creator:
Lester Holt
Air/Publish Date:
12/08/2009
Event Date:
12/08/2009
Resource Type:
Science Explainer
Copyright:
NBCUniversal Media, LLC.
Copyright Date:
2009
Clip Length:
00:04:00

Behind the breath-taking twists and turns of Olympic Freestyle Aerials is the science of angular momentum and moment of inertia. NSF-funded physicist Paul Doherty, Senior Scientist at The Exploratorium in San Francisco, and Olympic aerialist Emily Cook, show how these jumps actually come from three basic twisting techniques that you can try yourself.

Aerial Physics: Aerial Skiing

LESTER HOLT, anchor:

In the sport of Freestyle Aerials, skiers are judged on their ability to perform complex jumps in the air. Emily Cook, a 12-year veteran of the U.S. Freestyle team, and The Exploratorium’s Paul Doherty, a physicist funded by the National Science Foundation, show how these jumps actually come from three basic twisting techniques that you can try yourself.

HOLT: It's a sport of seemingly endless twists and turns. In Olympic Freestyle Aerials, skiers plummet down a steep ramp at up to 45-miles an hour before launching almost 50-feet into the air.

Then the real fun begins. Olympic Aerialist Emily Cook is part acrobat, part daredevil -- and an intuitive master of physics.

EMILY COOK (U.S. Ski Team – Freestyle): I think I was kind of born to be upside down. Some people are like that. It’s my most comfortable position.

HOLT: Any rotating mass has a property known in physics as angular momentum... created when torque - a force causing a free body to rotate - is applied to a mass, in this case an aerialist. Aerial skiers call this "contact twisting," and they create it in the way they push off the ramp.

COOK: If you were standing on the ground and you were to just jump up and do a full twist, your pushing off of the ground is what is causing the twist.

HOLT: Paul Doherty, Senior Scientist at The Exploratorium in San Francisco, shows how you can do “contact twisting” yourself.

Dr. PAUL DOHERTY (The Exploratorium): Watch me, I’ll leap into the air and turn 90 degrees by pushing on the ground before I leap. That was easy!

HOLT: The push-off is crucial: once in the air, aerialists cannot change their angular momentum. So how do they control their motion to execute the best spin in the air?

By controlling what's called their "moment of inertia" - which they do by moving their arms and legs in and out. A good illustration of this comes from the animal kingdom.

Cat: Meow!

HOLT: For more than a century, scientists have studied why a falling cat almost always lands on its feet.

Slow-motion photography reveals that by tucking its front legs and spreading its back ones -- all while rotating the upper and lower torso in opposite directions -- the cat can twist without touching anything.

Dr. DOHERTY: One part of the cat is turning one way and the other part’s turning the other. By changing the position of the mass, they can actually turn in the air.

HOLT: Aerialists perform the "cat twist" by making a hula-hoop motion with their hips.

COOK: If you picture yourself in a pool and you bend yourself at your waist, and you just kind of swivel yourself around, eventually you’ll start twisting.

HOLT: The last technique, called "tilt-twisting," uses precise arm movements to alter the speed and orientation of the spin.

COOK: If I were to go off the jump, I have both of my arms up, and if I were to drop my left arm, if you think about every action has an equal and opposite reaction, my body is going to go the other way.

Dr. DOHERTY: If I start out with my arms like this, I’m going to rotate my arms, right one back and left one forward. Watch that happens to my legs, and that was very effective in turning me.

HOLT: On the ground, twisting may look easy. But six stories above the ground -- with the whole world watching -- Olympic Freestyle Aerials is nothing less than a leap of faith in the laws of physics.

Close NBC Learn

Choose your product

NBC Learn K-12 product site
NBC Learn Higher Ed product site

For NBC Learn in Learning Management Systems please log in to your institution's Learning Management System web site and click "Browse NBC Learn".
For further assistance, please contact our NBC Learn Support Team and we'll be happy to assist you.

Start Your Free
day
Day Trial!
Close NBC Learn

FILTERING

If you are trying to view the videos from inside a school or university, your IT admin may need to enable streaming on your network. Please see the Internet Filtering section of our Technical Requirements page.

DVDs AND OTHER COPIES

Videos on this page are not available on DVD at this time due to licensing restrictions on the footage.

DOWNLOADING VIDEOS

Subscribers to NBC Learn may download videos and play them back without an internet connection. Please click here to find out more about subscribing or to sign up for a FREE trial (download not included in free trial).

Still have questions?
Click here to send us an email.

Close NBC Learn

INTERNATIONAL VISITORS

The Science of the Olympic Winter Games videos are only available to visitors inside the United States due to licensing restrictions on the Olympics footage used in the videos.

FILTERING

If you are trying to view the videos from inside a school or university, your IT admin may need to enable streaming on your network. Please see the Internet Filtering section of our Technical Requirements page.

DVDs AND OTHER COPIES

The Science of the Olympic Winter Games is not available on DVD at this time due to licensing restrictions on on Olympic footage.

DOWNLOADING VIDEOS

Subscribers to NBC Learn may download videos and play them back without an internet connection. Please click here to find out more about subscribing or to sign up for a FREE trial (download not included in free trial).

Still have questions?
Click here to send us an email.

Close NBC Learn

Choose your product

NBC Learn K-12 product site
NBC Learn Higher Ed product site

For NBC Learn in Blackboard™ please log in to your institution's Blackboard™ web site and click "Browse NBC Learn"

Close NBC Learn

If you have received a new user registration code from your institution, click your product below and use the "Register now" link to sign up for a personal account.

NBC Learn K-12 product site
NBC Learn Higher Ed product site

For further assistance, please contact our NBC Learn Support Team and we'll be happy to assist you.

Start Your Free
day
Day Trial!