Device used to measure the gravitational acceleration at the Earth's surface. It consists essentially of two small masses at different elevations that are supported at opposite ends of a beam. The latter is suspended from a wire that twists because the masses are affected differently by the force of gravity. When the wire is twisted, an optical system indicates the angle of deflection, and the torque, or twisting force, can be calculated. The torque is correlated with the gravitational force at the point of observation. Torsion balance may also refer to a device used in weighing, a type of equal-arm balance.
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Weighing device that uses the relation between the applied load and the deformation of a spring. This relationship is usually linear; that is, if the load is doubled, the deformation is doubled. Spring balances are widely used commercially. Those with high load capacities are frequently suspended from crane hooks and are known as crane scales.
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Difference in value over a period of time between a nation's imports and exports of goods and services. The balance of trade is part of a larger economic unit, the balance of payments, which includes all economic transactions between residents of one country and those of other countries. If a nation's exports exceed its imports, the nation has a favourable balance of trade, or a trade surplus. If imports exceed exports, an unfavourable balance of trade, or a trade deficit, exists. Under mercantilism a favourable balance of trade was an absolute necessity, but in classical economics it was more important for a nation to utilize its economic resources fully than to build a trade surplus. The idea of the undesirability of trade deficits persisted, however, and arguments against deficits are often advanced by advocates of protectionism.
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In international relations, an equilibrium of power sufficient to discourage or prevent one nation or party from imposing its will on or interfering with the interests of another. The term came into use at the end of the Napoleonic Wars to denote the power relationships in the European state system. Until World War I, Britain played the role of balancer in a number of shifting alliances. After World War II, a Northern Hemisphere balance of power pitted the U.S. and its allies (see NATO) against the Soviet Union and its satellites (see Warsaw Pact) in a bipolar balance of power backed by the threat of nuclear war. China's defection from the Soviet camp to a nonaligned but covertly anti-Soviet stance produced a third node of power. With the Soviet Union's collapse (1991), the U.S. and its NATO allies were recognized universally as the world's paramount military power.
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Systematic record of all economic transactions during a given period between residents (including the government) of one country and residents (including the governments) of other countries. The transactions are presented in the form of double-entry bookkeeping. The U.S. balance of payments, for example, records the various ways in which dollars are made available to foreigners through U.S. imports, U.S. tourist spending abroad, foreign lending, and so on. These expenditures are shown on the debit side of the balance. The credit side shows the various uses to which foreigners put their dollars, including paying for U.S. exports, servicing debts to the U.S., and the like. Foreign countries may acquire more dollars than they need to spend on U.S. goods and services and may hold the surplus or purchase gold or securities; or they may have fewer dollars than they need to purchase U.S. goods and services, and may acquire additional dollars by transferring gold, selling holdings in the U.S., and so on. Certain forms of transferring funds (e.g., large outflows of gold) are less desirable as a way of settling foreign debts than others (e.g., transfers of currency acquired through international trade). The International Monetary Fund helps address problems relating to balance of payments. Seealso balance of trade.
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Instrument for comparing the weights of two bodies, usually for scientific purposes, to determine the difference in mass. The equal-arm balance dates back to the ancient Egyptians, possibly as early as 5000 BC. By the early 20th century, it had been developed into an exquisitely precise measuring device. Electronic balances today depend on electrical compensation rather than mechanical deflection. The ultramicrobalance is any weighing device that serves to determine the weight of even smaller samples than can be weighed with the microbalance (which can weigh samples as small as a few milligrams), that is, total amounts as small as a few micrograms.
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