ASTRO–de Gmo 24→⅓

Log:√(2x+1y) Maßstab ŒUVRE[31] Base№7West

1920sTheory.#Number Photon⅜ dynamik ONDA

Addition and subtraction of two physical are indicated by: a+b and a−b. Multiplication of two physical quantities may be indicated in one of the following ways: ab a·b or a×b. Division of one quantity by another quantity may be indicated in one of the following ways: a÷b a/b ab⁻¹ or in any other way of writing the product of a and b−1. These procedures can be extended to cases where one of the quantities or both are themselves products, quotients, sums or differences of other quantities. If brackets are necessary, they should be used in accordance with the rules of mathematics. When a solidus is used to separate the numerator from the denominator, brackets should be inserted if there is any doubt where the numerator starts or where the denominator ends. EXAMPLES: Expressions with a solidus: a/bcd or a/(bcd), (⅜)sin_kx, a/b+c, a/(b−c), (a+b)/(c−d), a/b+c/d or (a/b)+(c/d). The argument of a mathematical function is placed in parentheses, brackets or braces, if necessary, in order to define its extent unambiguously. Examples: sin {2π(x−x₀)/∂} ->exp {(r−r₀)/µ} ->exp [−V(r)/kT] √(G/π) Parentheses may be omitted when the argument is a single quantity or a simple product: e.g., sin0, tankx. A horizontal overbar may be used with the square root sign to define the outermost level of aggregation, e.g., √G(t)/H(t). Since the rules of algebra may be applied to units and to physical quantities as well as to pure numbers, it is possible to divide a physical quantity by its unit. The result is the numerical value of the physical quantity in the specified unit system: {a}=a/[a]. The form “quantity/unit” should therefore be used in the headings of tables and as the labels on graphs for an unambiguous indication of the meaning of the numbers to which it pertains. EXAMPLES : Givenp =0.1013MPa, then p/MPa =0.1013 Givens =2200m/s, then v/(m/s) =2200 GivenT =295K, then T/K =295, 1000K/T ≈3.3898

During the height of the space race in the 1960s, legend has it, NASA scientists realized that pens could not function in zero gravity. They therefore spent years and millions of taxpayer dollars developing a ballpoint pen that could put ink to paper without needing gravitational force to pull on the fluid. But their crafty Soviet counterparts, so the story goes, simply handed cosmonauts grease pencils. Did NASA really waste that much money? Originally American astronauts, like the Soviets, wrote with pencils, according to NASA historians. Indeed, in 1965 NASA ordered 34 mechanical pencils from Tycam Engineering Manufacturing in Houston at $128.89 apiece: $4,382.50 in total. When these sums became public and caused an outcry, NASA scrambled to find a cheaper alternative. Pencils may not have been the best choice anyway. The tips could flake or break off, drifting in microgravity where they might harm an astronaut or equipment. And pencils are flammable—a characteristic NASA wanted to avoid in onboard objects after the Apollo 1 fire. Meanwhile Paul C. Fisher and his business, Fisher Pen Company, had invested a reported $1 million (none of it from NASA) to create what is now commonly known as the space pen. The device, patented in 1965, could write upside down, in frigid or roasting conditions (down to –50 degrees Fahrenheit or up to 400 °F), and even underwater or submersed in other liquids. If too hot, though, the ink turned green instead of its normal blue. isher offered the implement to NASA. Because of the earlier mechanical pencil fiasco, the agency hesitated. But after testing the tool—named the AG-7 “Anti-Gravity” Space Pen—the U.S. decided in 1967 to use it on future spaceflights. Fisher's pen makes up for a lack of gravity by storing ink in a cartridge pressurized with nitrogen at 35 pounds per square inch—more than twice as much force as sea-level atmospheric pressure on Earth. This pressure pushes the ink toward the tungsten carbide ball at the pen's tip. The ink, too, differs from that of other pens. It stays a gel-like solid until the movement of the ballpoint turns it into a fluid. The pressurized nitrogen also prevents air from mixing with the ink, so it cannot evaporate or oxidize. An Associated Press dispatch from February 1968 reported that NASA ordered 400 of Fisher's antigravity ballpoint pens for the Apollo moon mission program. A year later the Soviet Union ordered 100 pens and 1,000 ink cartridges to use on their Soyuz space missions, the United Press International said. The AP later noted that both NASA and the Soviet space agency received the same 40 percent discount for buying their pens in bulk. They both paid $2.39 per pen instead of $3.98—nowhere near millions. The space pen's mark on the Apollo program was not limited to facilitating writing in microgravity. According to its maker, the Apollo 11 astronauts, who were the first to walk on the moon, also wielded the pen to fix a broken engine-activating switch on the lunar module—a repair that enabled them to lift off from the moon for their rendezvous with the mother ship and their return to Earth. Since the late 1960s American astronauts and Russian cosmonauts have used Fisher's pens.