Olympic

The High-Speed Physics of Olympic Sledding, Explained

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There is more to the bobsled, luge and skeleton events than merely sliding down steep, icy slopes.

The High-Speed Physics of Olympic Sledding, Explained
Summer Britcher of United States during the Women’s Luge event on day three of the Beijing 2022 Winter Olympic Games at Sliding Park in Yanqing, China.

The following essay is reprinted with permission fromThe Conversation, an online publication covering the latest research.

Speed alone may be the factor that draws many sports fans to the bobsled, luge and skeleton events at this year’s Beijing Winter Olympics. But beneath the thrilling descents of the winding, ice-covered track, a myriad of concepts from physics are at play. It is how the athletes react to the physics that ultimately determines the fastest runs from the rest of the pack.

I study the physics of sports. Much of the excitement of a luge run is easy to miss – the athletes’ movements are often too small to notice as they fly by looking like nothing more than a blur on your television. It would be easy to assume that the competitors are simply falling or sliding down a track at the whim of gravity. But that thought merely scratches the surface of all the subtle physics that go into a gold-medal-winning performance.ADVERTISEMENT

GRAVITY AND ENERGY

Gravity is what powers the sleds down the ice-covered tracks in bobsled, luge and skeleton events. The big-picture physics is simple – start at some height and then fall to a lower height, letting gravity accelerate athletes to speeds approaching 90 mph (145 kph).

This year’s races are taking place at the Yanqing National Sliding Center. The track is roughly a mile long (1.6 km), drops 397 feet of elevation (121 meters) – with the steepest section being an incredible 18% grade – and comprises 16 curves.

Riders in the sledding events reach their fast speeds because of the conversion of gravitational potential energy into kinetic energy. Gravitational potential energy represents stored energy and increases as an object is raised farther from Earth’s surface. The potential energy is converted to another form of energy once the object starts falling. Kinetic energy is the energy of motion. The reason a flying baseball will shatter the glass if it hits a window is that the ball transfers its kinetic energy to the glass. Both gravitational potential energy and kinetic energy increase as weight increases, meaning there is more energy in a four-person bobsled team than there is in a one-person luge or skeleton for a given speed.

Racers are dealing with a lot of kinetic energy and strong forces. When athletes enter a turn at 80 mph (129 kph) they experience accelerations that can reach five times that of normal gravitational acceleration. Though bobsled, luge and skeleton may look easy, in reality they are anything but.

AERODYNAMICS

Most tracks are around a mile long (1.6 km), and the athletes cover that distance in just under a minute. Final times are calculated by adding four runs together. The difference between the gold medal and silver medal in the men’s singles luge at the 2018 Winter Olympics was just 0.026 seconds. Even tiny mistakes made by the best athletes in the world can cost a medal.ADVERTISEMENT

All the athletes start at the same height and go down the same track. So the difference between gold and a disappointing result comes not from gravity and potential energy, but from a fast start, being as aerodynamic as possible and taking the shortest path down the track.

While gravity pulls the athletes and their sleds downhill, they are constantly colliding with air particles that create a force called air drag, which pushes back on the athletes and sleds in a direction opposite to their velocity. The more aerodynamic an athlete or team is, the greater the speed.

To minimize drag from the air, luge riders – who are face up – lie as flat as possible. Downward-facing skeleton riders do the same. Whether in a team of two or four, bobsled riders stay tucked tightly inside the sled to reduce the area available for air to smash into. Any body positioning mistakes can make athletes less aerodynamic and lead to tiny increases in time that can cost them a medal. And these mistakes are tough to correct at the high accelerations and forces of a run.

THE SHORTEST WAY DOWN

Besides being as aerodynamic as possible, the other major difference between a fast and a slow run is the path riders take. If they minimize the total length taken by their sleds and avoid zigzagging across the track, riders will cover less distance. In addition to simply not having to go as far to cross the finish line, shortening the path means facing less drag from air and losing less speed from friction with the track.

Fans often miss the subtleties involved in turning and steering. The sleds for all the events sit on steel blades called runners. Bobsleds have two sets of runners that make contact with the ice. The front rider pulls on rings attached to pulleys that turn the front runners. Runners on luge sleds have curved bows at the front where riders place their calves. By moving their head and shoulders or flexing their calves, athletes can turn the luge. Skeleton riders lack these controls and must flex the sled itself using their shoulders and knee to initiate a turn. Even a tiny head movement can cause the skeleton to move off the optimal path.

All of these subtle movements are hard to see on television, but the consequences can be large – oversteering may lead to collisions with the track wall or even crashes. Improper steering may lead to bad turns that cost riders time.

Though it may appear that the riders simply slide down the icy track at great speeds after they get going, there is a lot more going on. Viewers will have to pay close attention to the athletes on those fast-moving sleds to detect the interesting facets of physics in action.

Scary Physics of ‘Curve 9’ Leads to Terrifying Olympic Luge Crash

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On Tuesday, Americans woke up to the news that Emily Sweeney of Team USA crashed during her luge run at the Olympics. Sweeney refused a stretcher and was able to walk away from the frightening accident — a tough-as-nails moment after careening down what’s essentially a roller coaster made of ice. Sweeney crashed after losing control during her final heat at Curve 9 — already notorious among Olympic sliders before the games even began.

Emily Sweeney, luge

The insane physics of the Winter Olympic’s “fastest sport on ice” means that coming out of a curve during the luge feels like, in the words of 2014 Olympian Chris Mazder, “launching into space on a rocket.” Sliders can reach speeds of 90 miles per hour after launching onto the ice with a 50-pound sled, propelling forward with spike-equipped gloves, and steering with their calves.

All that speed means that luge races are timed to one-thousandth of a second, and any time lost on a curve can ruin an athlete’s chances of placement. Defending Gold medalist Felix Loch of Team USA bumped into Curve 9 on Sunday, losing hundredths of a second and his chance at a 2018 medal.

Luge races take place on a track built with a length of 1,000 to 1,500 meters with a difference in elevation between 110 to 130 meters and an average slope of nine to 11 percent. Curve 9 is just one of 16 obstacles on Pyeongchang’s Alpensia Sliding Center track. As the athletes shoot down the U-shaped groove of the course they have to maneuver through left curves, right curves, hairpin curves, S-shaped curves, and a three-turn combination called a labyrinth.

But it was Curve 9 that everyone had been talking about before the Olympics kicked off. Before her own run, Sweeney described the curve as like “driving on a slanted road, but having your call getting pulled in a direction away from the way you’re steering.” It’s the angle of the curve that’s so rough — the turn sends the lugers to the right, but the track is actually designed to go 45 degrees to the left.

And when lugers hit the angle of the curve, their force against the ice can be as high as eight times that of gravity. The aerodynamic position of their body combined with the tiny amount of contact the steel (the name for the sled’s blades) makes with the ice minimizes the force of the drag, adding incredible speed to the centrifugal force that emerges as a reaction between the ice, the athlete, and the inertia. All of that means when a curve shoots you to the right, but the track goes to the left, retaining control is going to be incredibly difficult.

It’s ultimately what got Sweeney, who began sliding at severe and alternating angles after losing control after Curve 9. She was ultimately thrown from her sled into a tumble — a scary finale for a first-time Olympic run.

10 Top Ways to Stay Active as a Family.

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Story at-a-glance

·         Most families, adults and kids alike, are not getting enough physical activity

·         Combining family time with fitness is an easy way to increase physical activity and its associated health benefits

·         Scavenger hunts, family Olympics, water days, mileage goals and even doing chores together are examples of ways to stay active as a family

family-olympics

Despite the seemingly infinite benefits that physical activity has for your health, most people are not very active. The latest statistics from the US Centers for Disease Control and Prevention (CDC) state that just over 20 percent of adults are meeting recommended physical activity guidelines for both aerobic and muscle-strengthening physical activity!1

In case you’re wondering, those guidelines recommend at least 2.5 hours of moderate-intensity activity, or 1 hour and 15 minutes of vigorous-intensity activity a week, plus muscle-strengthening activities two or more days a week.

This trend extends to kids, too – only one in three US kids are physically active every day.2

It’s clear that many families also feel there aren’t enough hours in a day to spend quality time together, between work, school and other obligations, so it makes perfect sense to make your family time active time as much as possible. This way, you’re spending time together while also boosting your fitness and modeling a healthy lifestyle for your kids.

10 Top Ways to Stay Active as a Family

Going to the gym is fine for adults, but when kids are involved you’ve got to get more creative … and more fun!

1. Go on a Scavenger Hunt

Make a list of challenges (find an orange leaf, get a neighbor’s signature, snap a photo of a playground, etc.), split your family into teams, set a time limit and then head off (on foot or on bike) to see who can complete the most items.

2. Have a Water Day

Tossing water balloons, splashing in a kiddie pool and running through a sprinkler in the backyard are fun ways to stay cool and active on a hot summer day.

3. Set ‘Mileage’ Goals for the Weekend

Decide as a family how many steps, or how many miles, you want to travel over the weekend, then have fun trying to reach the goal. You can use pedometers to measure steps taken while running errands, going on hikes, playing tag and more, and can challenge the family to increase your goal each weekend.

4. Wash the Car

Washing the car uses key core muscles and can be a fun, bonding experience, especially if you take time to cool off with the hose, too.

5. Family Olympics

Get together with a group of families and compete in events like hula-hoops, 50-yard dash, relay race, basketball shoot, and an obstacle course. You can even make it an annual event!

6. Family Fitness Classes

If you like a more structured routine, try a fitness class designed for families, like stroller workouts, mom/dad and baby workouts or family yoga.

7. Do Chores Together

Vacuuming, washing windows, weeding the garden, raking leaves and even doing laundry work your muscles and burn calories while teaching your kids the value of responsibility. Make chores fun by setting a time limit and turning up the music while you work together as a family.

8. Plan Seasonal Outdoor Activities

Swimming, biking, canoeing and hiking are great in the summer, while sledding, ice skating, building a snowman or skiing are fun – and great for your fitness goals – in the winter.

9. Play Together

Tag, hide-and-go-seek, hop scotch, doing cartwheels and dancing in the kitchen are so much fun you won’t even realize it’s exercise in disguise.

10. Try Out Family Sports

A backyard game of softball or volleyball, shooting hoops or taking a trip to a golf course give you quality time as a family while staying active.

 

You Can Even Stay Active on Your Family Vacation!

Whether you’re going to grandma’s house for the weekend, planning a trip abroad or even having a “staycation,” family getaways are another opportunity to fit in fun activities that promote fitness. While on vacation, try:

Walking tours

Museums, zoos and theme parks (lots of walking!)

Collecting seashells

Jogging or walking on the beach

Using the hotel gym or doing bodyweight exercises in your hotel room (this will be mostly for mom and dad)

Power walking in the airport terminal

Snorkeling, hiking, beach volleyball and other outdoor activities

Exploring new locales by foot or bicycle

 

What Will Your Kids Gain by Staying Active?

Leading a physically active lifestyle is a good habit to instill in your child from an early age because although it’s never too late to start exercising, the sooner you do it, the better. Keeping kids active is a superb way to increase learning, focus and even test results.   As many of you reading this have likely experienced, if your mind is feeling cluttered or you’re having a mid-afternoon slump, a brisk walk or a quick workout can give you a renewed sense of clarity and focus. This is certainly true for kids and teenagers, too. There are a multitude of short- and long-term health benefits your child can gain from regular physical activity, including:

 

Reduced risk of diabetes and pre-diabetes

Improved sleep and mood

Stronger bones

Reduced restlessness or hyperactivity; helps decrease symptoms of ADHD

Improved immune system function

Decreased risk of suicide in teens

Weight loss

Increased energy levels

What Will YOU Gain by Staying Active?

The benefits that kids receive extend to adults as well, although as you age you’ll begin to reap the benefits of a lifetime of exercise in the form of better mobility, muscle mass and brain power. One of the primary benefits of exercise is that it normalizes your insulin and leptin levels, with the secondary benefits of weight loss and normalization of blood sugars. These basic factors in turn cascade outward, creating a ripple effect of positive health benefits, which include:

 

Improving your brainpower and boosting your IQ

Lowering your risk of heart disease and cancer

Building strong bones

Lowering your blood pressure

Curing insomnia

Losing weight

Relieving pain

Balancing your mood and fighting depression

Increasing your energy levels

Acquiring fewer colds

Lowering your risk of diabetes and reversing pre-diabetes

Slowing down your aging process

Limiting Screen Time is a Key Part of Staying Active

Once you’ve committed to staying active as a family, you may notice that the time you all spend sitting in front of a computer or the television naturally decrease, and this is a very good thing. More than two hours a day of screen time is associated with increased emotional and behavioral difficulties, regardless of the time spent exercising. According to one study:3

·Children who spent more than two hours a day watching TV or using a computer were 61 and 59 percent more likely to experience high levels of psychological difficulties, respectively

·Children who spent more than two hours a day watching TV, and also failed to meet physical activity guidelines, were 70 percent more likely to experience high levels of psychological difficulties

·This risk increased to 81 percent for children who used a computer for more than two hours a day while also failing to meet recommended exercise guidelines

So remember that it is imperative to limit your child’s TV, computer, and video game time in addition to encouraging your child to spend more time doing various forms of physical activity.

Source: mercola.com

 

 

 

Saudi Arabia: Let All Girls Play Sports.

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Rana Al Khateeb

Saudi Arabia should allow all girls in the kingdom, including public school students, to play sports in school. The government should formally clarify its position on sports for girls in government-funded schools and announce a national strategy to promote sports for girls at all levels of education.

The official Saudi Press Agency announced on May 4, 2013, that female students enrolled in private girls’ schools could take part in sports so long as they wear “decent clothing” and are supervised by female Saudi instructors within the tight regulations of the country’s Education Ministry.

“All of Saudi Arabia’s women and girls should be able to enjoy the social, educational, and health benefits of taking part in sports,” said Minky Worden, director of global initiatives at Human Rights Watch. “If the government can take down this barrier for private schools, it should give girls and women in publicly funded schools the same benefit.”

Although two women competed for Saudi Arabia at the Olympics in 2012 for the first time, women and girls are still not free to practice sports in the kingdom. The government should follow its announcement about private schools with a removal of public school barriers and an announcement of a strategy to make it happen, Human Rights Watch said.

Saudi Arabia is the only country in the world that still effectively bars girls from taking part in sport in government schools. There is no state sports infrastructure for women, with all designated buildings, sports clubs, courses, expert trainers, and referees limited to men. Discrimination against girls and women in sport still takes place at multiple levels in the kingdom, including:

·      The denial of girls’ physical education in state schools;

·      The refusal to license women’s gyms and sports clubs;

·      Discriminatory practices by the General Presidency for Youth Welfare, a youth and sports ministry responsible for promoting sport among Saudi youth and overseeing youth sports leagues, such as denying women’s participation in official sports clubs;

·      The denial of women’s representation on national sports bodies, resulting in the absence of competitive sports events for Saudi women athletes in the kingdom; and

·      The absence of government financial support for Saudi sportswomen in national, regional, or international competitions.

The two female athletes who represented Saudi Arabia in the 2012 London Olympics were Wujdan Shahrkhani, in judo, and Sarah Attar, in track and field. The International Olympic Committee (IOC)hailed the change, with the president, Jacques Rogge, announcing: “For the first time in Olympic history, all the participating teams will have female athletes. This is a major boost for gender equality.”

The Education Ministry has previously given indications that it might approve sports programs for girls in private schools. In December 2011, the Deputy Minister for Girls’ Affairs, Nora al-Fayez, wrote to Human Rights Watch:

[T]he ministry has issued no regulatory bylaws or rules that punish schools for female students practicing physical education; in fact there are sports activities in some private girls’ schools as part of their school curriculum and as extra-curricular activities.

The issue of girls’ physical education is under serious consideration as one of the priorities of the ministry’s leadership that regards physical education in schools as one of the necessities helping male and female students to stay healthy. The ministry is currently working on a comprehensive educational curriculum, starting with laying the infrastructure for the project and finishing with health and nutritional education, all within the national strategy for girls’ and boys’ physical education.

The Saudi authorities should extend the health and educational benefits that the Education Ministry cited to girls in public schools as well as private schools, Human Rights Watch said.

The government has carried out encouraging recent modest reforms for women, Human Rights Watch said, including on combatting domestic violence and licensing a female lawyer trainee. But as Human Rights Watch has documented in the report “Perpetual Minors,” the “guardianship” system and strict gender segregation limit women’s ability to take part in public life. Under this discriminatory system, girls and women are forbidden from traveling, conducting official business, or undergoing certain medical procedures without permission from their male guardians. All women remain banned from driving in Saudi Arabia.

Human Rights Watch has long urged the International Olympic Committee to use its leverage with Saudi Arabia to press its sports leaders to conform to the values and principles of the Olympic Movement by adopting policies that will benefit all Saudi women and girls. These include establishing a timeline and benchmarksfor introducing physical education as a subject for girls in public and private schools.

“The world cheered when Saudi women shared the Olympic spotlight, but millions of women and girls in Saudi Arabia are still stuck on the sidelines,” Worden said. ”This is a moment for the global sporting community to press Saudi Arabia to allow sports for women and girls, once and for all.”

Source: http://www.hrw.org

 

Kinesio tape: fad, fashion accessory, placebo?

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Kinesio tape. It was first brought to my attention during Euro 2012, with Italian players such as Buffon and Balotelli strapping this bright blue tape on the bodies. And since the Olympics has kicked off, I’ve seen it a lot more.

According to Kinesio it is adhesive strapping designed to provide muscle and joint support without restricting movement. However, it can only be applied by skilled practioners who have been on a course on how to apply it. Apparently, more than 4,000 people now know this technique and I should imagine many of the Olympic team doctors. However, there appears to be fairly minimal evidence that it can relieve pain or improve muscle strength.

From Reuters:

Kevin Anderson, managing director of Kinesio UK has said “There’s nothing magical in the tape, it certainly can’t improve your performance or make you into Superman, but the way people use the tape is to lift the skin, reduce the pressure and that helps relieve pain and swelling.”

Steve Harridge, a professor of human and applied physiology at King’s College London, said many athletes appeared to be wearing tape even when they had no injury, possible hoping for some preventative or enhancing effect.

“It may be a fashion accessory, and it may be just one of those fads that come along from time to time, but to my knowledge there’s no firm scientific evidence to suggest it will enhance muscle performance,” he told Reuters.

Both scientists agreed, however, that there may be a benefit, in the form of the placebo effect.

http://www.reuters.com/article/2012/08/01/us-oly-science-tape-day-idUSBRE86U0ZN20120801

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Have you noticed the increasing use of this tape? Can it really prevent injuries? Who is being trained in how to use it? Are athletes just using it as a fashion statement? Is it part of sporting superstitions?

Source: BJM/doc2doc