Why are there sixty seconds in a minute and sixty minutes in an hour?

Around 2400 BC, the ancient Sumarians, who used six as their mathematical base, divided a circle into 360 degrees, with each degree subdivided into another 60 parts, and so on. The Romans called these units minute prima, or first small part, and secunda minuta, or second small part. This system was perfect for round clock faces, and that’s why we use minutes and seconds as divisions of time.

What is a tsunami?

The Japanese word tsunami (pronounced soo-NAH-mee) means “harbor wave.” It is a huge volume of moving seawater—kind of like a giant wave—that can travel for thousands of miles across the sea and then approach the shoreline with the strength to destroy buildings, trees, wildlife, and people. Tsunamis can be triggered by an undersea earthquake, landslide, or volcanic eruption. The most frequent tsunami-maker is an undersea earthquake, which buckles the seafloor and displaces large volumes of seawater, creating a tsunami. This unique ocean event is not related to tides, although it is sometimes mistakenly called a tidal wave.

Posted on Categories Science

Who invented the zipper?

Like many inventions, the development of the modern zipper can be traced to a series of events. In 1893, Whitcomb Judson patented and marketed a “clasp locker,” a complicated hook-and-eye shoe fastener. Together with businessman Colonel Lewis Walker, Whitcomb launched the Universal Fastener Company to manufacture the new device. He did not use the word “zipper,” although many people often credit him as the zipper’s creator. Instead, it was Swedish-born Gideon Sundback, an electrical engineer who was hired to work for the Universal Fastener Company, Who gets the credit.

He was responsible for improving Judson’s fastener, and by December 1913, he had designed the modern zipper. Sundback increased the number of fastening elements from four per inch to ten or eleven, had two facing-rows of teeth that pulled into a single piece by a slider, and increased the opening for the teeth guided by the slider. Sundback also created a machine that was able to manufacture the zipper.

How can I get a baby brother instead of a baby sister?

There is no way specific way to place an order for a baby brother or a baby sister. The gender (boy or girl) of a baby is determined by whether the father’s fertilizing sperm has an X or a Y chromosome. An X chromosome will lead to a girl, and a Y to a boy. (Mothers always contribute an X chromosome.) Although scientific methods are available to help parents organize their chromosomes and take advantage of the fact that the “boy” sperm has less DNA than “girl” sperm, they can be expensive and unreliable. One method, called the Shettles method, recommends that if parents want a girl, they should plan to make a baby right around the time of ovulation.

At this time, the egg is as far away as possible from the incoming sperm so the long-distance runners of the sperm world, the X sperm, have a better chance of making it to the egg. For a boy, the method suggests that parents plan to make a baby about two to four days after ovulation. That way, the short-distance sprinting Y sperm can make it to the egg first. Many doctors say that although this method is based in science, it is no guarantee that a couple will have a baby boy or a baby girl.

Do all plants have leaves?

Most plants have leaves, even if they do not look like leaves. For example, blades of grass are really leaves. Mushrooms and other fungi do not have leaves, and seaweeds and lichens do not have leaves. Seaweed, a type of algae, also does not have flowers or roots. As an underwater plant, it usually clings to stones, shells, and rocks with its holdfast, a part of the plant that looks like roots. Unlike other plants that feed through their roots, seaweed takes its nutrients from the water in which it grows.

Where do babies come from?

Babies grow in their mother’s uterus, a special organ that houses the baby until it is born. At the start of pregnancy, a mother’s egg is fertilized, which makes a new cell. The cell divides quickly into many more cells. At about one week, this tiny mass, called an embryo, sticks to the wall of the uterus, and begins to grow. From the moment of conception, 46 chromosomes and tens of thousands of genes combine to determine a baby’s physical characteristics—the sex, facial features, body type, and color of hair, eyes, and skin. At the eighth week, the embryo is called a fetus.

By the end of the twelfth week, the fetus is completely formed and is able to make a fist, can turn his or her head, and can squint and frown. Until the baby is ready to come out, it grows inside its mother’s uterus. When the baby is ready to be born, at about 40 weeks, the mother starts to feel labor contractions. The uterus squeezes and pushes the baby out of the uterus and into the world.

How are newspapers made?

People usually read newspapers to get information about current events, things that are happening at the present time or have just occurred. When a good news story breaks, reporters are immediately sent out to gather as much information about the situation as possible and photographers take pictures that add visual information. When they return to the newspaper office, the reporters type their story into a computer, and camera film is developed into photos in a darkroom. The photographs are put into the computer with a device called a scanner. Increasing numbers of photographers use digital cameras, which means their photos do not have to be first developed on paper. They are automatically in digital, or computer-ready, format and can be transmitted over phone lines or via satellites just like e-mail or other electronic files. Once the photos are in digital format, the printed story and the pictures that illustrate it are arranged together. The story may take up part of a newspaper page or may extend for a few pages. Designers arrange all the stories and photos that make up a newspaper into visually appealing, easy-to-read pages on the computer screen. They are then printed out on pieces of clear film. Next, the film print of each newspaper page is laid on a light-sensitive metal plate. When it is exposed to a flash of bright light, shadows of the film’s letters and pictures are left on the plate. The shadows are permanently etched or marked into the plate when it is soaked in acid, which eats some of the metal away. What is left is a perfect copy of the film print of the newspaper page, with its words and pictures appearing as grooves in the metal.

The newspaper page is now ready to be printed on paper. The metal plate is first wrapped around a roller on a motor-driven printing press and coated with ink. After being wiped clean, ink still stays in the grooves. When paper (in big rolls) is passed under the roller, it is pressed into the grooves, and perfectly printed pages appear. This process is repeated for each newspaper page. As you can imagine, printing plants are enormous, with some presses standing three stories tall. These expensive machines (costing tens of millions of dollars) can print and sort up to 70,000 copies of a newspaper per hour. Once the press is done printing and sorting, the newspapers are bundled for delivery the next day to homes and newsstands.

Would ancient Greek athletes have had any chance against our well-trained modern Olympians?

At least two ancient Greek athletes would have done well in the modern games; their Olympic records stood until the twentieth century. Twenty-six hundred years ago, an athlete named Protiselaus threw a cumbersome primitive discus 152 feet from a standing position. No one exceeded that distance until Clarence Houser, an American, threw the discus 155 feet in 1928. In 656 BC, a Greek Olympian named Chionis leapt 23 feet, 1.5 inches, a long jump record that stood until 1900, When an American named Alvis Kraenzlein surpassed it by 4.5 inches.

Posted on Categories Science

What is dust, exactly, and why might it be bad for me?

Dust is made up of particles of all sorts of things. In places where people live, a great deal of dust comes from flakes of dead skin, which are being shed all the time. Dust mites, tiny microscopic creatures that feed on this dead skin, make up dust, too (including their waste and tiny skeletons). Particles of the environment contribute to dust as well: grit from the sidewalk, salt from the sea, dry earth, pollen from plants, pet dander, molds, and smoke from burning materials. And Earth gets 10 tons of dust from outer space every day, from the meteors that burn up as they enter our atmosphere. Sometimes these ingredients cause allergic reactions, such as sneezing and coughing.

Why do camels have humps?

Camels are the only animals with humps. A camel’s hump is a giant mound of fat, Which can weigh as much as 80 pounds (35 kilograms). The hump allows a camel to survive up to two weeks without food. Because camels typically live in the deserts of Africa and the Middle East, where food can be scarce for long stretches, their hump is key to their survival. When camels are born their humps are empty pockets of flexible skin. As a camel grows and begins to form its fatty tissue reserves, the humps begin to fill out and take shape.

The humps also come in handy for humans who have domesticated the camel. For thousands of years, people have used these strong, resilient creatures for transportation and for hauling goods. The two-hump, or Bactrian, camel was domesticated sometime before 2500 B.C.E., probably in northern Iran, northeastern Afghan – istan, and northern Pakistan. The one-hump, or Dromedary, camel was domesticated sometime between 4000 and 2000 B.C.E. in Arabia.