How do ski jumpers stay in the air for so long?（在线收听）

How do ski jumpers stay in the air for so long?

Transcript

Ski jumpers are in the air for about the length of a football field. A physicist explains how they manage to stay in the air for so long, as the Olympic sport wraps up for the 2022 Winter Olympics.

RACHEL MARTIN, HOST:

We're going to pivot now. Ski jumping wraps up today at the Winter Olympics. It's the sport where athletes speed down a big hill and then launch themselves into the air.

LEILA FADEL, HOST:

Ski jumpers are in the air for about the length of a football field.

AMY POPE: Looking at ski jumping, you find people that really look like they are flying. They're staying in the air for 5 to 7 seconds, which is so much longer than anything that we can do here, you know, on the mere mortal Earth.

FADEL: That's physicist Amy Pope.

POPE: We think about Michael Jordan, who can stay in the air for about a second when he jumps. And these people are managing to fly like a glider when they really have no extra support.

MARTIN: Pope teaches physics at Clemson University, and she wrote for Smithsonian Magazine about how ski jumping actually works.

POPE: So as the skiers jump off the end of the lift, what they're finding is that the air is rushing on them. They're falling down because gravity is pulling them down towards the Earth. But as they're falling down, the air underneath them is actually providing a lift force.

MARTIN: So skiers do whatever they can to maximize that effect.

POPE: You'll notice that their skis are splayed in a V-shape and their bodies are nearly parallel to the horizontal. So what they're trying to do is maximize that area so that the wind will push them up.

FADEL: Coordinators need to keep a careful eye on that wind.

POPE: You may notice as you're watching ski jumping that they're lifting and lowering the starting gate based upon the wind speed so that none of the skiers have an unfair advantage by having a large headwind.

FADEL: But Pope says the same wind that's pushing them up is also creating drag.

POPE: That drag is actually serving to slow them down over time, and as they slow down, the lift decreases, and so the flight cannot continue forever, just like anything that sails through the sky.

MARTIN: Now, the physics are so important here that there are very specific rules about what athletes can wear, including their suits. Their suits need to be extremely formfitting.

POPE: If the suits are a little bit loose, what's going to happen is it's going to be like they're wearing a squirrel suit. And they're going to be able to essentially get more lift because they have a larger surface area that they can present.

MARTIN: Five ski jumpers were disqualified from the Winter Games this year because officials said their suits didn't comply with the rules. But, listen, if you want to see all the physics in play for yourself, the men's final is this morning. Fly, skiers, fly.

[POST-BROADCAST CLARIFICATION: The article that Amy Pope wrote about ski jumping was originally published by The Conversation and was republished by Smithsonian magazine.]