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How many hairs grow on the human head?

Each hair on the human head grows between two to six years, then rests for a few months, after which it falls out. A new hair then replaces the previous hair, using the same hair follicle. Human hair follows a specific growth cycle with phases called the anagen, catagen and telogen phases. All three phases occur on the human head simultaneously, with different hairs in different phases of growth.

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Why is there wind?

The National Center for Atmospheric Research explains that wind can be described as air that is moving with both direction and speed. Wikipedia explains that there is also wind in outer space, which is the movement of gases or charged particles from the sun throughout space. Wind direction is always expressed in terms of the direction from which the wind is blowing, never the direction in which it is going. Easterly winds are those that come from the east and move towards the west.\nIn addition to direction, wind speed is described by terms such as a breeze or gale. Gale-force winds are much h..

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What are some facts about metallurgy?

The first known use of metals by humans occurred in the late Paleolithic period. Gold, silver, copper and tin were among some of the first metals extracted and used in ancient times. The discovery that the mixing of copper and tin produces a stronger metal, bronze, ushered in the Bronze Age around 3500 B.C. The next major advancement in metallurgy occurred around 1200 B.C. with the discovery of new techniques to extract iron from its ore, commencing the Iron Age.\nModern civilization depends on strong metals, including enormous amounts of steel, copper and aluminum used to make skyscrapers, au..

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What are examples of condensation nuclei?

Condensation depends on a nongaseous particle to use as a vessel for the liquid formed from water vapor. These particles are called cloud condensation nuclei.\nCloud condensation nuclei can be formed naturally, or they can be man-made. Water vapor can condense around pollution particles created by burning fossil fuels in factories. Water can also condense around sea salt, bacteria and volcanic ash, forming distinctive clouds. Each different cloud condensation nuclei has an effect on the composition and type of cloud that is formed from them.

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What would happen if the Earth were tilted at 45 degrees?

An axial tilt of 45 degrees would bring more heat to bear on the hemisphere facing the sun. More solar radiation would strike the temperate zones and the poles during summer, and the equator would also be affected. During winter, the reverse would occur, with far colder temperatures near the poles.\nThe cycle of day and night would also be affected. In the summer months of a given hemisphere, more of the planet would be perpetually on the day side, similar to how there are bands near the poles that receive 24 hours of sunlight or nightfall depending on the season.\nEarth would experience more ..

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At what temperature does water boil?

As the altitude increases, the boiling point of water decreases. Below sea level, the boiling point of water increases.\n\nThe purity of the water also affects its boiling point. For instance, salt water boils at a higher temperature than pure water.\n\nIt is easy to boil water. A pot is filled with water and placed on the stove. The heat is turned to high. When large bubbles rise from the bottom of the pot to the surface of the water, it is boiling.

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How tall is 70 inches?

Seventy inches is just slightly less than the average height of an American man. According to the Centers for Disease Control, in 2010 the mean height of men ages 20 and older in the United States was 69.3 inches. This is not the tallest worldwide. For example, a 2013 study in the Oxford Economic Papers found that, as early as 1971, the average height for men ages 21 and over in Great Britain was 70 inches.

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How much does the moon weigh?

The moon does have mass, which can be taken as a stand-in for weight. The moon's mass is roughly 7.3477×10^22 kilograms, or 73.5 million million million metric tonnes. This is the figure that would most likely register on a standard scale if the moon could be brought to Earth and weighed and if the Earth's gravity acted equally on all parts of the moon.

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How are ocean ridges formed?

When tectonic plates meet, they are essentially unstoppable forces, which means something must give. Usually, one plate slides beneath the other, lifting the edge of the second plate, creating a subduction zone. As the subduction zone grows, magma seeps in through the cracks and edges of the plate, quickly cooling as it hits the surface. These underwater actions have raised tall mountain range systems totalling about 37,000 miles in length altogether.\nAround the ridge, the cracks and gaps that allow magma to escape also allow ocean water to seep in. When it meets the deep-earth magma, it pick..

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What are the four functions of the skeleton?

Movement is possible because bones act as levers and also provide support for muscles and tissue. Without them muscle and tissue would have no attaching point. Skeletal bones also protect vital organs, such as the heart, lungs and brain. Bones also provide a storage area for red blood cells, platelets and minerals which are necessary for healthy functioning of the entire body.

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