Why do we call a leg injury a “charley horse”?

The phrase charley horse has its roots in baseball. At the beginning of the twentieth century, groundskeepers often used old and lame horses to pull the equipment used to keep the playing field in top condition.

The Baltimore Orioles had a player named Charley Esper, who, after years of injuries, walked with pain. Because his limp reminded his teammates of the groundskeeper’s lame horse, they called Esper “Charley Horse.”

How do robots like ASIMO and Mahru work?

Robots like ASIMO and Mahru are sophisticated, expensive, highly technologically advanced machines that are built upon major components found in humans. Robot technicians use the inner workings of the human body as the model for the robots that they make. This modeling ensures that their robots are as lifelike as possible. First, the robot technician designs the five major components he or she will put into the robot: a body structure, a muscle system, a sensory environment, a power source, and a brain system.

Next, they build an intricate machine made up of electrical circuits, electrical valves, piston cylinders, electric motors, solenoids, hydraulic systems, and more—each plays a specific role in getting the robot to work. Every robot has a computer that controls everything else within its body. Many robots can talk and some can even smell, taste, and hear. To get the body of a robot moving, the computer must “tell” the specific part to move. If the technician wants the robot to do something new once it has been made, he or she writes a new computer program. In some cases, if the task is too big for the robot’s wiring system, new parts need to be installed. NUMBERS AND COUNTING

Which tree produces the largest nut?

The coco de mer tree, a palm that only grows today on two islands in the Seychelles, produces both the largest seed (each weighs about 44 pounds [20 kilograms]) and the largest nut in the world. The nut, which takes six to seven years to mature and another two years to germinate, is sometimes called the sea coconut or Seychelles nut. When early explorers first discovered the nut, they thought it came from a mythical tree at the bottom of the sea.

Sixteenth-century European nobles decorated the nut with jewels as collectibles for their private galleries. Today, the coco de mer is a rare protected species.

Does the brain feel pain?

Technically, no. While it is responsible for receiving and transmitting all messages of pain for the whole body, the brain itself does not have pain receptors.

That means that, if you could somehow gain access to another person’s brain, you could poke it or pinch it and that person would not feel the pain.

How do seeds become plants?

Once seeds are fully developed, they need a good place to grow. If they just fell to the ground beneath their parent plant, they would struggle, competing against each other for sunlight, water, and minerals. Most seeds need to travel—by wind, water, or with the help of insects and other animals—to better places to germinate, or start to grow into new plants. Some seeds, like those from conifer and maple trees, have wings attached. Others, like those of dandelions, have parachutes made of tiny hairs. Both features allow the seeds to be carried great distances by the wind, and they sometimes land in spots that are good for germination. Water carries other seeds to good growing places; the hard, watertight shell of a coconut, for instance, allows it to travel many miles at sea before finding a beach where conditions are suitable for growth.

Seeds sometimes have to wait a long time before they find good places to grow, places where the sun, moisture, and temperature are right. Most seeds are designed for the wait, protected by a hard outer pod (except those of conifers). Some seeds wait years to germinate, and some just never do. But inside each seed pod is a baby plant, or embryo, and endosperm, a supply of starchy food that will be used for early growth if germination takes place. Then a tiny root will reach down into the soil, and a tiny green shoot will reach up, toward the light.

Does a Venus flytrap really snap up live flies?

Indeed, it does. A Venus flytrap is a carnivorous plant that attracts, captures, and kills insects and digests and absorbs their nutrients. The leaves of the Venus flytrap, Which can open wide, have short, stiff hairs called trigger hairs. When anything touches these hairs enough to bend them, the two lobes of the leaves snap shut, trapping whatever is inside. The “trap” will shut in less than a second, capturing flies and other insects.

When the trap closes over its prey, finger-like projections called cilia keep larger insects inside. In a few minutes the trap shuts tightly and forms an air-tight seal in order to keep its digestive fluids inside. These fluids help the plant digest prey. At the end of the digestive process, which takes from 5 to 12 days, the trap reabsorbs the digestive fluid and reopens. The leftover parts of the insect blow away in the wind or are washed away by rain.

How do frogs make their loud croaking sound?

Frogs are able to make their croaking noises because they have simple vocal cords that have two slits in the bottom of the mouth. These slits open into what is called a vocal pouch. When air passes from the lungs through the vocal cords, a sound is produced. The inflating and deflating vocal pouch makes the sound louder or quieter.

That sound changes depending on the kind of frog there are as many different kinds of croaks as there are frogs! Frogs croak for the same reasons that many animals make noises: to track down and then select a mate, and to protect their territory from other male frogs.

Which city is the largest?

There are many cities around the world that are “big,” meaning they have more than 10 million people living in them. Tokyo, Japan, ranks the largest, since it has 33.2 million people living in the city, according to 2005 estimates. The next biggest cities in order of size are São Paulo, Brazil (17.7 million), Seoul-Incheon, South Korea (17.5 million), Mexico City, Mexico (17.4 million), Osaka-Kobe-Kyoto, Japan (16.4 million), and New York City (about 8 million people).

Most of these cities are located in different places around the globe. In the United States, after New York, Los Angeles is the biggest city (with almost 4 million people), and then Chicago (with almost three million people). Populations of cities are constantly changing as people move in and out of them, according to the U.S. Census Bureau, a government organization that estimates how big or small cities are based on their populations, or the number of people living in them.

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.

The bald eagle’s head is covered with white feathers. So why is it called the bald eagle?

Because one meaning of the word “bald” that is not commonly used anymore refers to white markings. “Bald” used to refer to people with white hair. Due to excessive hunting, environmental pollution, and loss of habitat, the bald eagle population became dangerously low at one point, prompting the U.S. Congress to pass a law protecting it. Bald eagles were once listed by the U.S. Fish and Wildlife Service as an endangered species, meaning they were close to being extinct. Thanks to the laws protecting it, these birds have rebounded a bit. They are now listed as threatened, which means they are not as close to being extinct as they once were, but their numbers are still few (only about 50,000 in the United States), and it is illegal to hunt them.