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How tall is the average 13-year-old?

In general, a baseline for average teenage height is hard to determine. During the adolescent years, a child's body experiences growth spurts that lead to major changes in both height and weight. Thus, there are flaws in most statistics on average teenage height, as the height of a 13-year-old changes quickly. Girls in particular experience dramatic changes in height, weight and body-fat distribution during the early teen years.

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What is a nonpolar covalent bond?

If the two atoms have equal electronegativity, they form a nonpolar covalent bond. If the electronegativity is only slightly unequal, the two form a polar covalent bond, and if there is a large difference between the two, the result is an ionic bond. Both polar and nonpolar covalent bonds can only occur between two nonmetallic atoms, unlike ionic bonds, which occur between a metal and a nonmetal atom.\nSome common elements that form nonpolar covalent bonds are iodine and oxygen. An atom of iodine normally has seven electrons in its outer shell, which means it is searching for one more electron..

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What are signal transduction pathways?

Three examples of signal transduction include the signaling by nerve growth factor, long-term depression and phosphorylation of tyrosine hydroxylase. Nerve growth factor is responsible for many functional aspects of the sensory neuron, including differentiation and survival. Long-term depression plays a role in signaling between parallel fibers and Purkinje cells in the cerebellum. Tyrosine hydroxylase is involved with nervous system regulation.

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How much does a car weigh?

The increased weight is largely due to more powerful and efficient engines. In addition, cars tend to have better seats, more safety features and additional legroom, all of which increase vehicular weight. In general, heavier cars burn less gas, which reduces the amount of pollution they emit when compared to older models. However, heavier cars do pose a danger to others. Being hit by one of these vehicles increases an individual's chance of dying in an accident by 47 percent.

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What is a list of inert gases?

According to the University of California Davis, Henry Cavendish was the first to discover the inert gases in 1875 by chemically removing all the oxygen and nitrogen from a container of air. When he was done, a small percentage of the gas volume did not react, these were the inert gases. William Francis later isolated the gases by dissolving uranium minerals in acid. These chemists set the stage for others to discover and name the individual gases of Group 18 of the periodic table.\nThey are called inert gases because they are extremely nonreactive due to the fact their valence shells are fill..

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How do wind water pumps work?

Wind water pumps are comprised of many different parts, all of which work together to move water. These parts include blades, a rotor, pinion gears, bull gears, a shaft, a yoke, a pump rod, Pitman arms, a pump cylinder, a piston and two check valves. The wind starts the process of the movements of the parts to push through the water. For example, when the wind moves the wheel, it forces the shaft to start moving the pinion gears, which then move the bull gears.The bull gears start the movement of the Pitman arms, which in turn causes the yoke and pump rod to move up and down. The movement of t..

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Is air a fluid?

Fluid refers to a substance through which atoms can flow freely. While there are differences between the ways liquids and gases behave, there are enough similarities to make this categorization useful. Plasmas are also considered fluids.\nThe field of fluid mechanics contrasts with that of solid mechanics. Not all substances, however, fall into one of these two categories. Rheology deals with these substances, which include sludges, muds and certain bodily fluids.

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What are some examples of echinodermata?

There are around 7,000 species that fall under the classification of echinodermata, otherwise known as echinoderms. At least 800 of these can be found in the waters that make up the Great Barrier Reef. The name "echinodermata" comes from the Greek "echinoderma," meaning "spiny skin."\n\nEchinoderms are easy to spot because of their radial symmetry, since all echinoderm species have five arms or multiples of five arms. They also have a calcium carbonate shell covered by skin. Echinoderms have fairly rudimentary respiratory systems that allow them to take oxygen in through tube feet and simple g..

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What is the protoplanet hypothesis?

According to the protoplanet hypothesis, the planets that form farther from the forming star tend to be larger because the heat from the sun evaporates the gases closer to it, reducing the mass of the forming bodies. Greater mass allows the larger planets to accumulate mass faster due to their greater gravitational pull. The rocky planets toward the interior of solar systems have much less hydrogen and other gases in their compositions.

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How many elements are there known to science?

All of the known elements are arranged in a grid called the periodic table. Each element is organized in the periodic table by its atomic number from hydrogen in the top left corner to ununoctium in the lower right corner. Each row of the table is called a period.\nThe columns on the periodic table are referred to as groups. Elements within a specific group generally share similar chemical properties and are classified in the following manner.\nThe elements in the group on the far left are alkali metals. These elements are highly reactive to water, producing alkaline solutions and hydrogen gas..

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