| Abstract from DBPedia | In science and engineering, the weight of an object is the force acting on the object due to gravity. Some standard textbooks define weight as a vector quantity, the gravitational force acting on the object. Others define weight as a scalar quantity, the magnitude of the gravitational force. Yet others define it as the magnitude of the reaction force exerted on a body by mechanisms that counteract the effects of gravity: the weight is the quantity that is measured by, for example, a spring scale. Thus, in a state of free fall, the weight would be zero. In this sense of weight, terrestrial objects can be weightless: ignoring air resistance, the famous apple falling from the tree, on its way to meet the ground near Isaac Newton, would be weightless. The unit of measurement for weight is that of force, which in the International System of Units (SI) is the newton. For example, an object with a mass of one kilogram has a weight of about 9.8 newtons on the surface of the Earth, and about one-sixth as much on the Moon. Although weight and mass are scientifically distinct quantities, the terms are often confused with each other in everyday use (e.g. comparing and converting force weight in pounds to mass in kilograms and vice versa). Further complications in elucidating the various concepts of weight have to do with the theory of relativity according to which gravity is modeled as a consequence of the curvature of spacetime. In the teaching community, a considerable debate has existed for over half a century on how to define weight for their students. The current situation is that a multiple set of concepts co-exist and find use in their various contexts.重さ（おもさ、weight）または、重量（じゅうりょう、weight）は、物体についての厳密な物理量ではなく、日常語として使われる文脈では、全く異なる次の２つの意味がある。 1.
* 物体の質量(mass)の意味。計量単位はキログラム(kg) 2.
* 物体に働く重力の大きさ、すなわち力(force)の意味。計量単位はニュートン(N) かつては工学分野においては、物体の質量とそれが及ぼす力（または荷重）を厳密には区別せずに議論や計算を行っていた（重力単位系）が、現在では厳密に区別している。 (Source: http://dbpedia.org/resource/Weight) |
