Category: Physics

Damping Down Danger

2/3/2023

Sneed B. Collard III

Connecting Science and Kids

Several years ago, I rode the world’s fastest elevator to the top of one of the world’s tallest buildings—Taipei 101. Shaped like an elegant stalk of bamboo, Taipei 101 soars 1670 feet above the island nation of Taiwan. However, the engineers who designed the building faced two monumental challenges. The first is that dozens of earthquakes shake Taiwan each year. The second is that in an average year, Taiwan gets hammered by three or four hurricanes, or typhoons.

            How, engineers wondered, could they keep people comfortable inside Taipei 101 when it swayed back and forth? More important, how could they keep the building from getting damaged or collapsing in a massive earthquake or 100 mile-per-hour winds?

            One solution: a damper ball.

            Damping devices are weighty objects that can reduce the motion of a bridge, building, or other structure. In the case of Taipei 101, engineers placed the damper ball near the top of the building—the part that sways the most. The ball is hung from thick cables inside the building and rests on giant springs or “dampers.”

            One of Isaac Newton’s basic laws of physics is that an object at rest tends to stay at rest—and the damper ball proves it. Every time Taipei 101 starts swaying, the damper ball wants to stay where it is and “pulls back” on the building, reducing how far the building moves. When the building sways in the opposite direction, the process repeats itself—but in the reverse direction. Of course the building also pulls on the damper ball, but the ball’s movements are restricted by the dampers it presses against.

            Does the system work? You bet. The damper ball inside of Taipei 101 reduces the building’s movement by 30 to 40 percent!

            Of course not just any damping device could protect an enormous building like Taipei 101. Taipei’s damper ball weighs 1.5 million pounds—as much as two fully-loaded jumbo jets. It is composed of 41 circular steel plates that stand taller than a one-story house. In 2008, when a giant earthquake hit mainland China, the people of Taiwan could feel it hundreds of miles away. The damper ball did its job, resisting Taipei 101’s movement, keeping the building safe. During Typhoon Soudelor in 2015, the damper again worked like a charm, protecting the building against 100- to 145-mile-per-hour winds.

            Besides protecting Taipei 101, the damper ball has become a major tourist attraction. Each year, thousands of visitors ride to the 89th floor. They take selfies next to the damper ball. They even take “Damper Baby” souvenirs home with them. If you’re ever lucky enough to visit Taiwan, check it out!

Left: Taipei 101 is a landmark skyscraper in Taipei, Taiwan. The building was officially classified as the world's tallest in 2004, and remained such until the completion of the Burj Khalifa in Dubai in 2010. Alton Thompson, Wikimedia Commons
Above: The damper is a steel sphere 18 feet across. Supported by eight steel cables, it swings like a pendulum. Armand du Plessis, Wikimedia Commons

The damper ball is visible between the 89th and 91st floor of Taipei 101 and has become an attraction for tourists.

Sneed B. Collard III is author of more than eighty award-winning children’s books as well as a new book for educators, Teaching Nonfiction Revision: A Professional Writer Shares Strategies, Tips, and Lessons.
Sneed is a dynamic speaker and offers school and conference programs that combine science, nature, and literacy. To learn more about him and his talks, visit his website,.
To learn more about the damper ball and watch how it performed during Typhoon Soudelor, check out this article and video: http://www.thorntontomasetti.com/taipei-101s-tmd-explained/

MLA 8 Citation
Collard, Sneed B. "Damping Down Danger." Nonfiction Minute, iNK Think Tank, 10
01 2018, www.nonfictionminute.org/the-nonfiction-minute/
Damping-Down-Danger.

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A Raindrop Quiz

12/8/2022

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Alexandra Siy
Science through the lens

Which lunch food has a shape that resembles a falling raindrop?

a.      orange

b.     potato chip

c.      hot dog

d.     hamburger bun

e.      all of the above

f.       none of the above

               If you chose (f), you’re like most people who think raindrops are shaped like tears.

               If you chose (e), you’re probably just hungry.

               In either case you’re wrong.

               That leaves us with lunch. Let’s start from the top.

               Choice (a), orange, is a sphere. Water droplets are spherical because water is cohesive, meaning it sticks to itself. The “skin” that holds the drop together is surface tension and the reason insects can walk on water.

               If you chose (a), you made a logical choice based on the properties of water, but you are wrong. Notice that you were not asked to identify the shape of a raindrop sitting on a leaf. You were asked to identify the shape of a falling raindrop. (Always read questions carefully!)

               Moving down the list to (b), we encounter the potato chip. Potato chips come in many shapes, ranging from relatively flat to completely crumpled. Have you ever seen a raindrop that looks even a little bit like a potato chip? If you chose (b) you are wrong, but have a good sense of humor.

               Choice (c), hot dog, is an interesting option. Could a spherical drop of water morph into the cylindrical shape of a hot dog? After all, a hot dog is a cylinder with a hemisphere (half sphere) on each end. Could a water droplet in free fall separate itself into two hemispheres with a long drip of water in between? Although this is an imaginative idea, the laws of physics make it impossible.

               Choice (d), hamburger bun, is the only remaining choice, and is the correct answer. Here’s why:

               A raindrop is acted upon by three forces: gravity, buoyancy, and drag. Gravity is the force that pulls the drop toward the earth, while buoyancy of the surrounding air pushes it upward and keeps it from falling. When the force of gravity is greater than the force of buoyancy, the raindrop falls. The air around it creates drag, slowing the drop down to its maximum speed. In the process, the sphere is distorted into a shape that resembles a hamburger bun.

               Got it? Now, you may go to lunch.

Water forms spherical drops because of cohesion and surface tension. ©Alexandra Siy

Air pressure at the bottom of the falling drop is greater than at the top. (Image courtesy of NASA)

Bugs bite, drink blood, and rob food from gardens and fields. They can even kill plants, animals, and, occasionally, people. Is bugging a crime? In her latest book, Bug Shots, Alexandra Siy compiles "rap sheets" on several of the major categories of bugs and takes a very close look at some of the types of insects in an engaging text. For more information, click here.
Alex Siy is a member of iNK's Authors on Call and is available for classroom programs through Field Trip Zoom, a terrific technology that requires only a computer, wifi, and a webcam. Click here to find out more.

MLA 8 Citation
Siy, Alexandra. "The Race for the Sky." Nonfiction Minute, iNK Think Tank, 7 Dec. 2017, www.nonfictionminute.org/ A-Raindrop-Quiz.

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How to Make Your Friends Think You're Super Strong

4/7/2022

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Vicki Cobb

The Master Chef of Kids' Hands-on Science

No one wants to mess with someone who is super strong! Even if you’re undersized, especially if you’re undersized, you’ve got to try the two tricks in this Minute .

Here’s the first challenge:  Bet another person can’t remove your hand from the top of your head.   The challenge-taker must try to remove your hand according to your rules. Otherwise, it’s cheating. Sit on the floor. Place your hand with your fingers spread apart firmly on the top of your head. Have your friend grasp your lower arm next to your elbow. Now let him/her pull upward, trying to lift your hand from the top of your head.

Chances are excellent that you’ll be lifted off the ground before your palm parts from its perch.

Why is this so? If you’ve studied simple machines you may have learned about a mechanical advantage. That’s how a simple machine such as a lever can multiply your strength or speed. In this case, you’re putting your friend at a mechanical disadvantage.   Your arm is a lever. In order to move your hand from the top of your head, you need an upward force near your hand. If that force is delivered as far away from your hand as possible, it loses its power. It’s easy to remove your hand if you deliver an upward force near your wrist. But at your elbow? No way! Got it?

Here’s another trick with the secret sauce of physics. Bet you can keep ten people from shoving you into a wall. Place your hands against a wall with your fingers spread and your arms outstretched. Have ten people line up behind you, hands on the shoulders of the person in front of them. At the count of three, have everyone push on the person in front of them as hard as they can. I mean, really lean in.

You, hero of the day, can hold them all off and not bend your elbows.

Why? Actually, each person absorbs the force of the person behind them so that you are not experiencing the cumulative force of ten people, only the force of the person directly behind you. So pick someone smaller than you to be that first person.   If you’re not super strong, you can still be super smart.

If you don’t want to try this yourself, look at my videos of other people doing the challenges. Maybe you’ll change your mind.

If you like these bets, check out Vicki Cobb’s new release of We Dare You! You might want to join her We Dare You! National Video Project and make more videos yourself from her book. Learn more about it here.

Vicki Cobb is a member of iNK’s Authors on Call. You can invite her to your class through the magic of videoconferencing. Learn more about it here.

MLA 8 Citation
Cobb, Vicki. "How to Make Your Friends Think You're Super Strong." Nonfiction
Minute, iNK Think Tank, 23 Mar. 2018, www.nonfictionminute.org/
the-nonfiction-minute/How-to-Make-Your-Friends-Think-Youre-Super-Strong.

1 Comment

A Bouncing Ball Like You've Never Seen

3/29/2022

2 Comments

Vicki Cobb
The Master Chef of Kids’ Hands-on Science

You can’t play tennis unless you know where the ball will be after it bounces. You can’t pass a basketball unless you understand how to angle a bounce so that it goes where you want it to go. As long as the court surface is smooth and flat, a ball’s bounce is very predictable. Its path depends on gravity and on the strength and direction of the force that sets the ball in motion. Thanks to high speed photography we can get a closer look at a bouncing ball.

This is a multiple exposure photograph of a bouncing ball. It was taken in complete darkness with the camera shutter open while a high-speed flashing light, called a stroboscope or strobe, flashed 30 times a second. Each flash produced an image.

Here’s what you can learn from this photo: The ball is moving fastest where the images are farthest apart and slowest where they are closest together. When the ball is falling, it speeds up. After it bounces and moves opposite the pull of gravity, it slows down at exactly the same rate as it sped up when it was falling until it stops for an instant and starts falling again. Each time it collides with the ground, some energy is lost. That’s why each bounce loses altitude. If the bounce were perfect, no energy would be lost, every bounce would be as high as the last and the ball would bounce forever.

A strobe also captures the split second when a tennis ball is struck by a racket. The collision flattens the ball, and stretches the strings and distorts the frame of the racket, all in .005 seconds. If these objects kept their distorted shapes, most of the force of the collision would be absorbed. But they are elastic—they restore themselves to their original shapes after they collide. This restoring force is transferred to the ball to change its direction and help add to the speed of the athlete’s swing. The fastest serve leaves a racket at 130 miles an hour. In a rally, a ball-racket collision changes direction of the ball so it is not as fast as a serve, maybe 70 miles per hour. Since the distance between images made by a strobe tells how fast an object is moving, strobes are part of the instruments used to measure the speed of balls from a tennis racket and a baseball pitcher.

Photo credit: C. E. Miller, MIT

Would you believe that you could throw an egg across the room without breaking it? Burn a candle underwater? Vicki Cobb's We Dare You! is a gigantic collection of irresistible, easy-to-perform science experiments, tricks, bets, and games kids can do at home with everyday household objects. Thanks to the principles of gravity, mechanics, fluids, logic, geometry, energy, and perception, kids will find countless hours of fun with the selections included in this book. If you would like to make a We Dare You Video, click here.
Vicki Cobb is a member of iNK's Authors on Call and is available for classroom programs through Field Trip Zoom, a terrific technology that requires only a computer, wifi, and a webcam. Click here to find out more.

MLA 8 Citation
Cobb, Vicki. "A Bouncing Ball Like You've Never Seen." Nonfiction Minute, iNK
Think Tank, 5 Feb. 2018, www.nonfictionminute.org/the-nonfiction-minute/
a-bouncing-ball-like-you've-never-seen.

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Isaac Newton's Wonder Years

3/28/2022

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Kerrie Logan Hollihan
Teaching the Power of Wonder

   In spring 1665 a college student named Isaac Newton studied natural philosophy, what we call “science.” Back then, a good student could learn everything to know about the natural world. But plague, the Black Death, came to England. Cambridge University closed. Isaac went home to Woolsthorpe.

            For two years Isaac thought about his studies during four years at university. He’d always been thoughtful—not the best at games, making friends, or minding sheep. But everybody knew Isaac Newton liked to think. Folks told time by the sundial he’d drawn on a wall.

            Home at Woolsthorpe, Isaac’s learning about science and math bubbled up in his head like yeast rising in a loaf of bread.

            So... Newton unplugged. His mind roamed like that of an artist or composer. He was driven by the need to create—not paintings or symphonies, but questions.

            “Why do things always fall down?”

            “Why does the earth move around the sun?

            “Why doesn’t the moon fall onto the earth?”

            “Does everything ‘up there” work like things work ‘down here?’”

            Isaac Newton answered his questions with three science rules, Newton’s Laws of Motion.

            At Woolsthorpe, Newton grappled with the concept of moving objects. He worked out the math to find the area under curves. He called this math fluxions. Today we call this calculus, useful for launching rockets or tracking TV signals.

            Once back at Cambridge, Newton said nothing until he read someone else’s paper on fluxions. Newton published a better paper. Soon he was Cambridge’s top math professor.

            Isaac Newton wondered another twenty years. He played with prisms in a dark room and theorized that white light comprises the visible spectrum of red, orange, yellow, green, blue, indigo, and violet. He practiced alchemy and chemistry, looking for the legendary philosopher’s stone to turn base metals to gold. In 1687, Newton published our most important science book, the Principia.

            In the Principia, Newton showed how laws of gravity and motion work the same at great distances—far off in space, or in your classroom. We accept these ideas, but in 1687 many still had medieval beliefs that sun, moon, planets, and stars all traveled in their own crystal spheres.

            Yes, Newton wondered about A LOT:

Gravity
Forces
Mass
Inertia
Math
Motion
Light
God
???

Whatever interests you, I hope you’ll think about it—a lot! Like Isaac Newton, take time to WONDER!

Sir Isaac Newton was an English mathematician, astronomer, theologian, author and physicist who is widely recognized as one of the most influential scientists of all time and a key figure in the scientific revolution. Based on a portrait by Godfrey Kneller, 1702, via Wikimedia Commons

Sir Isaac Newton's own first edition copy of his Philosophiae Naturalis Principia Mathematica with his handwritten corrections for the twentieth edition. Photograph Andrew Dunn via Wikimedia Commons

Trinity College, the part of the University of Cambridge where Newton worked and lived. Library of Congress

This statue of the young Isaac Newton stands at the Oxford University Museum of Natural History. Look carefully around his feet for a hint on what he is wondering about. If you can’t figure it out, then read about Newton and gravity.
Wikimedia Commons

Featuring 21 hands-on projects that explore the scientific concepts Isaac Newton developed, Kerrie Logan Hollihan's Isaac Newton and Physics for Kids paints a rich portrait of the brilliant and complex man and provides readers with a hands-on understanding of astronomy, physics, and mathematics. A time line, excerpts from Newton's own writings, online resources, and a reading list enhance this unique activity book.

MLA 8 Citation
Hollihan, Kerrie Logan. "Isaac Newton's Wonder Years." Nonfiction Minute, iNK
Think Tank, 21 Feb. 2018, www.nonfictionminute.org/the-nonfiction-minute/
isaac-newtons-wonder years.

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Damping Down Danger

A Raindrop Quiz

How to Make Your Friends Think You're Super Strong

A Bouncing Ball Like You've Never Seen

Isaac Newton's Wonder Years

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