Mass
Introduction
Mass is a fundamental property of matter in physics. It is a measure of an object's resistance to acceleration when a force is applied. It also determines the strength of an object's gravitational attraction to other bodies.
Definition
In physics, mass is defined as the quantity of matter in a physical body. It is usually measured in kilograms, a base unit in the International System (SI) of Units. The mass of an object is not dependent on gravity, thus it is not affected by the location of the object in the universe.
Inertia and Mass
Inertia is the resistance of any physical object to any change in its state of motion. This includes changes to the object's speed, direction, or state of rest. Inertia is directly related to mass; the greater an object's mass, the greater its inertia, or the more force it takes to change its motion.
Gravitational Mass
Gravitational mass is the quantity of matter in an object that determines the strength of the gravitational field it generates, and its gravitational interaction with other bodies. It is the mass as measured by a balance scale, which compares the force of gravity on the object being measured with the force of gravity on a known mass.
Inertial Mass
Inertial mass is a measure of an object's resistance to acceleration when a force is applied. It is determined by applying a known force to an object and measuring the acceleration that results. Inertial mass is the mass as defined by Newton's second law of motion.
Mass–Energy Equivalence
The mass–energy equivalence principle, proposed by Einstein in his theory of relativity, states that the energy of an object is equal to the mass of the object multiplied by the speed of light squared. This is expressed in the famous equation E=mc^2.
Mass in Quantum Physics
In quantum physics, particles are described by wavefunctions, mathematical functions that give the probability of finding a particle in a certain state. The mass of a particle is related to the frequency of its wavefunction.
Mass in Particle Physics
In particle physics, the mass of subatomic particles is usually given in terms of the electronvolt (eV). The mass of a particle is related to its energy and momentum according to the principles of quantum mechanics.