Recent Trends in Network Security and Applications Third International Conference, CNSA 2010, Chennai, India, July 23-25, 2010 Proceedings. Passive gravitational mass measures the gravitational force exerted on an object in a known gravitational field. Active gravitational mass measures the gravitational force exerted by an object. Although some theorists have speculated that some of these phenomena could be independent of each other, current experiments have found no difference in results, whatever way is used to measure mass: Inertial mass measures an object's resistance to being accelerated by a force (represented by the relationship F = ma). There are several distinct phenomena which can be used to measure mass. In modern physics, matter is not a fundamental concept because a definition of it is elusive. Thus, any stationary body having mass has an equivalent amount of energy, and all forms of energy resist acceleration by a force and have gravitational attraction. However, at very high speeds, special relativity states that the kinetic energy of its motion becomes a significant additional source of mass. In Newtonian physics, mass can be generalized as the amount of matter in an object. This is because weight is a force, while mass is the property that (along with gravity) determines the strength of this force. Mass is not the same as weight, even though mass is often determined by measuring the object's weight using a spring scale, rather than comparing it directly with known masses.Īn object on the Moon would weigh less than it does on Earth because of the lower gravity, but it would still have the same mass. The basic SI unit of mass is the kilogram (kg). It also determines the strength of its mutual gravitational attraction to other bodies.

It is the measure of an object's resistance to acceleration (a change in its state of motion) when a net force is applied. In physics, mass is a property of a physical body. For other uses, see Mass (disambiguation). For the substance of which all physical objects consist, see Matter.

This article is about the scientific concept.

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