 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 In this MIT YouTube, a ball is dropped in front of a meter stick and lit by a strobe light. A long exposure photograph captures the position of the ball at each evenly spaced flash of light. The acceleration of the ball can then be measured from the photo.  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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In October, 1891, 23-year-old Manya Sklowdowska arrived in Paris to attend the Sorbonne, France’s great university. She had saved money, working as a governess to get there. She was determined to make the most of her studies in science and math. Right away she was noticed partly because she was Polish, although she had changed her first name to a French version, Marie, to fit in better. She always sat in the front row of all her classes because her French was not yet fluent and she didn’t want to miss anything. She also was one of only a few female students. In a university full of smart people, she worked hard to excel. She ultimately finished first in her class and went on to make major scientific discoveries. What made Marie so single-minded and determined? Behind it all was a great love for science, a love she shared with her husband, Pierre Curie, whom she met in 1894. At that time, science was uncovering unimaginable truths in chemistry and physics. New discoveries were being made at a breath-taking pace. Science was like a game and it attracted many players. Why? 1. There was a Nobel Prize for winners, those who discovered a big idea about the natural world. There was only one nature to discover but people came at it from many directions. 2. It was collaborative—scientists shared their discoveries by publishing papers. 3. It was competitive—the papers described procedures so that scientists could check each other’s work. It kept everyone honest. The best work got the most attention. 4. The discoveries could be applied to solve problems for people. X-rays, light bulbs, phonographs, photographs, movies, and telephones would not have been possible without science. 5. The biggest prize was the idea of the atom and its structure. Many scientists contributed to modern atomic theory, including Marie. Marie Curie won the Nobel Prize twice for her work. At a time when women didn't even have the right to vote, she was a working mother of two daughters, a single mother after she was widowed in 1906, the founder of the Radium Institute for research and she brought the x-ray to the battlefield in WWI. She believed that science could save the world, that scientific discoveries belonged to everyone. And she refused to benefit financially from her discoveries. She lived by the highest principles of honesty and integrity. She was a true champion of the science game.
 DK Biography: Marie Curie tells the story of the discoverer of radium, from her childhood in Warsaw, to her experiments with radioactivity in Paris, to her recognition as one of the preeminent scientists of her time. Filled with archival photographs and amazing fact boxes, this biography paints Marie Curie as the brave and brilliant scientist that she was. 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. "Marie Curie: An Elite Player in the Science Game." Nonfiction Minute`, iNK Think Tank, 30 Jan. 2018, www.nonfictionminute.org/ the-nonfiction-minute/Marie Curie-An-Elite-Player-in-the-Science-Game.  
 At left in the back is a fresh spinach leaf that has been treated with trehalose, frozen and defrosted.. The droopy one has been frozen and defrosted without trehalose. It's what is giving us hope that we may soon be able to defrost a salad. When it comes to preserving a fresh taste in food to be eaten at some later time, nothing beats freezing it. That was the discovery made by Clarence Birdseye in 1924. He had been working in northern Canada and noticed that fish caught by the native Canadian Inuits froze almost instantly in the frigid winter air. It was just as delicious when cooked and eaten months later as it was on the day it was fresh. Birdseye figured that if food was frozen quickly at very cold temperatures, large ice crystals couldn’t form to damage the food and make it mushy. His flash-freezing process made him very rich. The problem isn’t so much the freezing of food as what happens when it’s defrosted. See for yourself. Stick a stalk of celery in your freezer. The next day defrost it. Want to eat it? Compare it to a fresh unfrozen stalk. The perky structure of fresh celery is destroyed by ice. Water has the very unusual property of expanding and taking up more space when it changes into ice than when in a liquid state. That’s why ice cubes float and frozen unopened soda cans bulge. Expanding ice crystals destroy the cell walls of plants. Quickly freezing fresh food keeps the ice crystals smaller than slower freezing, but they are still large enough to destroy the cell walls of delicate vegetables like spinach or lettuce. But if you defrost frozen spinach from the supermarket it is beyond limp. So a salad you can defrost and serve as if it were fresh has seemed like an impossible dream. Federico Gomez, a Swedish scientist, is working to change this. Like Birdseye he took a close look at nature, specifically at plants that stay alive in very cold climates. He discovered that they contain a sugar called trehalose (tree-HAL-ose) that works like a natural antifreeze. Could he find a way to get trehalose into spinach leaves? If so, would the trehalose protect the structure of the spinach and keep it crisp after defrosting? This picture shows the results. The leaf on the left was treated with trehalose. The one on the right was untreated. He froze and defrosted both. The treated leaf is as crisp as if it had never been frozen! Just because there is success in a lab doesn’t mean a defrosted salad will show up on your dinner plate any time soon. But these results are enough to keep the research going. Move over Clarence Birdseye!
 Cobb has revised her classic book, Science Experiments You Can Eat. While doing her research, she came across this work of Frederico Gomez. She bought trehalose on line and soaked some slices of parsnip and zucchini in a trehalose solution, hoping that the sugar would be absorbed by the plant cells. But when she froze them and defrosted them, it didn't work. Dr. Gomez got the sugar inside the plant cells by removing some water from between the cells in a vacuum chamber, soaking the leaves in a trehalose solution (which moved the sugar into the spaces outside the cells) and then exposing the leaves with a mild electric shock to get the sugar through the cell walls. Vicki didn't have the equipment to do all this but she tried anyway. The book was published in 2016. 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. "Why You Can't Defrost a Salad...Yet." Nonfiction Minute, iNK Think Tank, 11 01 2018, www.nonfictionminute.org/the-nonfiction-minute/ Why-You-Can't-Defrost-a-Salad-Yet.  
Think you might like to be a helicopter pilot? If so, here’s what the U.S. Flight Aptitude Selection Test for helicopter pilots says: “Helicopter pilots must pass some of the most demanding physical tests of any job in the military. To be accepted for pilot training, applicants must have excellent vision and be in top physical condition. They must have very good eye-hand-foot coordination and have quick reflexes.” A sense of balance is also extremely important because sometimes instruments alone are not enough to keep a helicopter oriented properly in the air. Pilots may have to make very subtle corrections. So here’s a test for balance. Be forewarned. Not many people can do this, maybe one in twenty. 1. Stand at attention. 2. Make two fists and extend your arms straight down by your sides. Point your index fingers to the ground. 3. Close your eyes. 4. Bend one leg back at the knee so that your lower leg is parallel to the floor and you are standing on one foot. Don’t let your foot droop. You must maintain your knee at a right angle. 5. Keep your eyes closed and hold this position for ninety seconds. 6. Try not to shake. I learned about this from a Scotsman who told me about this test to qualify for the British Royal Air Force. He couldn't pass it, nor could I. In fact, no one I knew could rise to the helicopter pilot challenge except a Navy pilot in my family. He held the position perfectly for two minutes. Solid like a rock. No problem. It’s clear that when it comes to certain skills not everyone is equal. Some people are not even close. So very few people are in the running to become helicopter pilots. You're probably not one of them but this may change with training.  This young man is an athlete who actually wants to be a helicopter pilot. He passed the test and is holding the correct position. Not sure if the bare feet helped. Photo credit: Alexandra Siy  Vicki Cobb is a former science teacher with a M.A. in secondary school science. She is also the founder and president of iNK Think Tank, the group that is producing The Nonfiction Minute. Thanks, Vicki! Check out How Could We Harness a Hurricane?. To find out more about this book and other books that Vicki has written, 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. "Take the Helicopter Pilot Challenge." Nonfiction Minute, iNK Think Tank, 4 Jan. 2018, www.nonfictionminute.org/ Take-the-Helicopter-Pilot-Challenge.  
 A land surveyor sends a heliograph to his partner more than 100 years ago. He must have been fluent in Morse Code How do you know it’s the holiday season? There are lights everywhere sending that message. But that’s not the only kind of message light can send. A little more than 100 years ago when a telegraph began to become popular, people sent wireless messages called heliographs. They were made of flashes of light in Morse code (the same pattern of short and long as used in telegraphs) by reflecting the sun’s rays with a mirror. When the mirror was at a particular angle to the sun, it reflected a flash of bright light to observer miles away.  Note where the red light from the bulb emerges on the opposite side. Some internally reflected light is emerging from a ridge in the glass. Photo by Alexandra Siy Maybe there’s another way to send light. Put a holiday light on one rim of a heavy glass measuring cup or dish. See where the light emerges on the rim on the opposite side. Move the light back and forth and watch what happens on the other side. The light travels down the side, and bends to go across the bottom and up the other side, but if you look at the cup sideways you can’t see the beam. Light stays inside the glass as it travels from rim to rim. Could we make something like a wire from glass that can transmit light? Absolutely! An optical fiber is a flexible, transparent fiber made of glass or plastic that acts as a wire for light. Imagine a beam of light entering a fiber at exactly the right angle to bounce off the inside wall of the fiber where it meets the air. It is then reflected at exactly the same angle to bounce off the opposite wall making a zig-zag path until it reaches the end of the fiber. This internally reflected light stays inside the glass fiber as it travels at the speed of light. HUGE quantities of all kinds of information—words, pictures, music, and videos—can now be sent through optical fibers, much more than through wires. A modern network with copper wiring can handle about 3,000 telephone calls at the same time, while a similar system using fiber optics can carry more than 30,000! So when you hit “send,” know that your holiday message is a blinking beam of light, bouncing off the inside walls of a glass fiber on its speedy journey to friends and family. How ‘bout that!  Fiber optics can be made into holiday decorations. Note the bright light emerging from the ends of the fibers.  Want to know more about optics? Have a look at Vicki Cobb's book Light Action! She co-authored it with her son, Josh, who is an optical engineer and her other son, Theo, drew the pictures. It's full of experiments that let you use optics to: -Bend light around corners - Stop time with a pair of sunglasses - Capture light on a silver tray - Magnify pictures with an ice cube - Pour light into your palm - Project a big-screen image from your small TV - Fool a doorbell with a bike reflector! For more information, go here. Vicki 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. "What Can You Learn from a Holiday Light and a Glass Cup?" Nonfiction Minute, iNK Think Tank, 14 Dec. 2017, www.nonfictionminute.org/ What-Can-You-Learn-from-a-Holiday-Light-and-a-Glass-Cup.  |
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