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How many years are in a light year?

Light years are used to simplify the discussion of extreme distances. The distance that light travels in a second is about 186,000 miles, making that the distance of a light second. The star nearest to the Earth is roughly 24 trillion miles, or slightly over 4 light years, away. Light years may also indicate the age of a visible astrophysical event, because it took that much time for the light of that event to reach the Earth.

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What is Stokes' law of viscosity?

The website School Physics provides the equation, viscosity = 2gr^2(d1-d2)/9v, where g is a gravitational constant, r is the radius of the sphere, d1 is the density of the particle, d2 is the density of the liquid, and v is the terminal velocity of the particle. School Physics further explains that the velocity increases as the sphere sinks, until the frictional drag due to viscosity is balanced by gravity, at which time the velocity remains constant. Frictional drag is less for large spheres, but the terminal velocity is greater, as compared to small spheres. According to Michigan Technologic..

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What are the different crochet hook sizes?

Differences in product labeling confuse consumers, according to the Craft Yarn Council website. It advises manufacturers to use both labeling techniques to show size by letter, number, and millimeter to prevent confusion. Due to lobbying by the Craft Yarn Council, many manufacturers will implement changes to promote the clear labeling of crochet hook size in new product packaging and new crochet patterns.

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What are some facts about tundra?

The word "tundra" comes from "tunturi," a Finnish word that refers to treeless plains. Tundra is one of the most extreme biomes on Earth, mostly because of its harsh, cold temperatures and lack of fresh water, which create a desert-like environment. The tundra around the Arctic has an average temperature of 10 to 20 degrees Fahrenheit.\nPermafrost is a unique feature of a tundra environment. Permafrost reaches from the ground to over 1,000 feet below the surface and is composed of frozen soil and dead plants.\nFew plants live in tundra, as the growing season lasts for only 50 to 60 days in som..

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How has a cactus adapted to life in the desert?

Cacti do not have leaves, but instead have a fixed spine. The fixed spine loses less water than leaves, so the plant can photosynthesize throughout the dry season. Cacti have very shallow roots to soak up water immediately after rainfall, and they also have thick, expandable stems to store all of the water they absorb from the ground. Because of these adaptations, cacti are able to survive in the desert where most plants would die.

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What effect does acid rain have on rocks?

Acid rain's ability to dissolve marble and limestone makes it hazardous to buildings and outdoor monuments. Igneous and metamorphic rocks exposed to acid rain can poison ecosystems; stone such as granite and gneiss release toxic aluminum ions into the environment when exposed to acid rain.\nRainwater is naturally more acidic than other forms of water due to dissolved carbon dioxide. The carbon dioxide becomes carbonic acid when dissolved in water, giving rainwater a pH between 5 and 6. Acid rain contains sulfuric acid and nitric acid, rendering it even more acidic than ordinary rainwater...

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Why do cells divide?

Cell division is a form of reproduction, but each resulting cell in normal cell division is identical to the original. Normal cell division is called mitosis, and this results in two identical cells. These cells continue life and perform the same functions as the original cell. They grow and eventually undergo division themselves. This is the type of division for most cells.\nThe other type of cell division is called meiosis, and it is how the body produces eggs or sperm. The process is the same for both males and females. A single egg goes through many of the same stages that are in mitosis, ..

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What are examples of plant tropisms?

There are several different examples of tropisms in plants. Gravitropism, or the response to gravity, causes roots to move towards gravity, or down into the soil, to reach water and minerals. It also causes stems to move away from gravity, so that leaves and stems will be in a position to intercept light.\nPhototropism is the response in plants to unidirectional light coming from one source, such as a lamp or beam of sunlight. Cells on the shaded side of the stem elongate more than the cells on the lit side, causing the stem to turn toward the light.\nThigmotropism is plant response to touch. ..

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What is the pKa value of acetone?

The related pKb value for acetone is -5.2. The pKb value measures the basicity of a substance and is found by subtracting the pKa value from 14. Acetone is represented by the chemical formula C3H6O and has a molar mass equal to about 58.08 grams per mole. It is a colorless liquid with a pungent odor. Acetone is an organic compound.

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What is pyruvate converted to before entering the citric acid cycle?

The citric acid cycle is the second step in cellular respiration for eukaryotic organisms. While glycolysis occurs in the cytoplasm of the cells, the citric acid cycle and the final step in the process, known as the electron transport chain, take place in the mitochondria of the cells. Prokaryotic organisms also engage in the citric acid cycle. However, as explained by About.com, bacteria conduct the citric acid cycle in the cytoplasm of the cells, rather than in mitochondria. Most of the adenosine triphosphate produced via cellular respiration occurs during the portions of the cycle that occu..

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