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Conservation law

In physics, a conservation law states that a particular measurable property of an isolated physical system does not change as the system evolves.

One particularly important physical result concerning conservation laws is Noether's Theorem, which states that there is a one-to-one correspondence between conservation laws and differentiable symmetries of physical systems. For example, the conservation of energy follows from the time-invariance of physical systems, and the fact that physical systems behave the same regardless of how they are oriented in space gives rise to the conservation of angular momentum.

A partial listing of conservation laws that are said to be exact laws, or more precisely have never been shown to be violated:

There are also approximate conservation laws. These are approximately true in particular situations, such as low speeds, short time scales, or certain interactions.


Conservation of energy

The law of conservation of energy is an empirical law of physics. It states that the total amount of energy in an isolated system remains constant over time (is said to be conserved over time). A consequence of this law is that energy can neither be created nor destroyed: it can only be transformed from one state to another. The only thing that can happen to energy in a closed system is that it can change form: for instance chemical energy can become kinetic energy.

Albert Einstein's theory of relativity shows that energy and mass are the same thing, and that neither one appears without the other. Thus in closed systems, both mass and energy are conserved separately, just as was understood in pre-relativistic physics. The new feature of relativistic physics is that "matter" particles (such as those constituting atoms) could be converted to non-matter forms of energy, such as light; or kinetic and potential energy (example: heat). However, this conversion does not affect the total mass of systems, because the latter forms of non-matter energy still retain their mass through any such conversion.

Today, conservation of “energy� refers to the conservation of the total system energy over time. This energy includes the energy associated with the rest mass of particles and all other forms of energy in the system. In addition, the invariant mass of systems of particles (the mass of the system as seen in its center of mass inertial frame, such as the frame in which it would need to be weighed) is also conserved over time for any single observer, and (unlike the total energy) is the same value for all observers. Therefore, in an isolated system, although matter (particles with rest mass) and "pure energy" (heat and light) can be converted to one another, both the total amount of energy and the total amount of mass of such systems remain constant over time, as seen by any single observer. If energy in any form is allowed to escape such systems (see binding energy), the mass of the system will decrease in correspondence with the loss.

A consequence of the law of energy conservation is that perpetual motion machines can only work perpetually if they deliver no energy to their surroundings.

History

Ancientphilosophers as far back as Thales of Miletus had inklings of the conservation of which everything is made. However, there is no particular reason to identify this with what we know today as "mass-energy" (for example, Thales thought it was water). In 1638, Galileo published his analysis of several situations—including the celebrated "interrupted pendulum"—which can be described (in modern language) as conservatively converting potential energy to kinetic energy and back again. It was Gottfried Wilhelm Leibniz during 1676–1689 who first attempted a mathematical formulation of the kind of energy which is connected with motion (kinetic energy). Leibniz noticed that in many mechanical systems (of several masses, mieach withvelocityvi),

\sum_{i} m_i v_i^2

was conserved so long as the masses did not interact. He called this quantity the vis vivaor living force of the system. The principle represents an accurate statement of the approximate conservation ofkinetic energy in situations where there is no friction. Many physicists at that time held that the conservation of momentum, which holds even in systems with friction, as defined by the momentum:

\,\!\sum_{i} m_i v_i

was the conserved vis viva. It was later shown that, under the proper conditions, both quantities are conserved simultaneously such as in elastic collisions.

It was largely engineers such as John Smeaton, Peter Ewart, Karl Hotzmann, Gustave-Adolphe Hirn and Marc Seguin who objected that conservation of momentum alone was not adequate for practical calculation and who made use of Leibniz's principle. The principle was also championed by some chemists such as William Hyde Wollaston. Academics such as John Playfair were quick to point out that kinetic energy is clearly not conserved. This is obvious to a modern analysis based on the second law of thermodynamics but in the 18th and 19th centuries, the fate of the lost energy was still unknown. Gradually it came to be suspected that the heat inevitably generated by motion under friction, was another form of vis viva. In 1783, Antoine Lavoisier and Pierre-Simon Laplace reviewed the two competing theories of vis viva and caloric theory. Count Rumford's 1798 observations of heat generation during the boring of cannons added more weight to the view that mechanical motion could be converted into heat, and (as importantly) that the conversion was quantitative and could be predicted (allowing for a universal conversion constant between kinetic energy and heat). Vis viva now started to be


From Yahoo Answers

Question:1. What is the law of conservation of Matter 2. What is the law of conservation of Mass and how does it differ to the law of conservation of Matter 3. Who founded the law and how/why did s/he do it 4. How did this discovery help scientists in today's world Please help me

Answers:law of conservation of matter - a fundamental principle of classical physics that matter cannot be created or destroyed in an isolated system, it is merely transformed from one form to another. The law of conservation of MASS/MATTER is the same thing just two different names. Check out the wikipedia link i gave. Its very helpful. 3. Read HISTORY on Wikipedia link. 4. Although mass is always conserved, it is NOT conserved in a NUCLEAR reaction, since in a Nuclear reaction, mass is converted to ENERGY via Einsteins equation E=mc^2. I am a chemical engineer and I use the law of conservation of mass and energy everyday. If I know the mass going into my system, then no matter what chemical reactions take place I will always know the mass coming out of the system. For simplification: If i have a pipe going into a boiler, with water and I measure the mass of liquid water coming out, I can instantly calculate the amount of steam I am producing: Mass in = Mass out Total water in = Liquid water out + Steam Therefore Steam = Total water in - Liquid water out

Question:1. What is the law of conservation of Matter 2. What is the law of conservation of Mass and how does it differ to the law of conservation of Matter 3. Who founded the law and how/why did s/he do it 4. How did this discovery help scientists in today's world Please help me

Answers:1 / 2 The law of conservation of mass, also known as principle of mass/matter conservation is that the mass of a closed system (in the sense of a completely isolated system) will remain constant over time. The mass of an isolated system cannot be changed as a result of processes acting inside the system. A similar statement is that mass cannot be created/destroyed, although it may be rearranged in space, and changed into different types of particles. This implies that for any chemical process in a closed system, the mass of the reactants must equal the mass of the products. 3. Beginnings of the theory of conservation of mass were stated by Epicurus (341 270 BC). Describing the nature of the universe, he wrote: "the sum total of things was always such as it is now, and such it will ever remain," and that nothing is created from nothing, and of the conservation of mass was stated by Nas r al-D n al-T s (1201 1274) during the 13th century. He wrote that a body of matter is able to change, but is not able to disappear. The principle of conservation of mass was first outlined clearly by Antoine Lavoisier (1743 1794) in 1789, who is often for this reason referred to as an initiator of modern chemistry. However, Mikhail Lomonosov (1711 1765) had previously expressed similar ideas during 1748 and proved them by experiments. Others who anticipated the work of Lavoisier include Joseph Black (1728 1799), Henry Cavendish (1731 1810), and Jean Rey (1583 1645). 4. Once understood, the conservation of mass was of great importance in changing alchemy to modern chemistry. When chemists realized that substances never disappeared from measurement with the scales (once buoyancy effects were held constant, or had otherwise been accounted for), they could for the first time embark on quantitative studies of the transformations of substances. This in turn produced ideas of chemical elements, as well as the idea that all chemical processes and transformations (including both fire and metabolism) are simple reactions between invariant amounts or weights of these elements.

Question:could some give me a somewhat simple deffinition

Answers:The Law of Conservation of mass is simple - you can not destroy or create mass (or matter). That's one of the fundamental concepts of physics - matter cannot be created nor destroyed, although it may be rearranged.

Question:i need this for a grade 10 chemistry test. If you could also explain the difference between endo and exothermic reactions and the whole single/double displacement deal that would be great!

Answers:The Law of Conservation of Mass states that in a chemical reaction, the total mass of the reactants is always equal to the total mass of the products. Endothermic Reation is the reation that requires heat/energy Exothermic Reaction is the reaction that releases heat/energy. (Notice the ex, so think of the word exhale). Single Displacement: one atom is exchanged into another molecule Double Displacement: this involves a joint exchange from a group of atoms to another molecule.

From Youtube

Law of Conservation of Mass :Explaining the law of conservation of mass.

Law Of Conservation Of energy in a Simple Pendulum :Check us out at www.tutorvista.com The law of conservation of energy is an empirical law of physics. It states that the total amount of energy in an isolated system remains constant over time (is said to be conserved over time). A consequence of this law is that energy can neither be created nor destroyed, it can only be transformed from one state to another. The only thing that can happen to energy in a closed system is that it can change form, for instance chemical energy can become kinetic energy. Albert Einstein's theory of relativity shows that energy and mass are the same thing, and that neither one appears without the other. Thus in closed systems, both mass and energy are conserved separately, just as was understood in pre-relativistic physics. The new feature of relativistic physics is that "matter" particles (such as those constituting atoms) could be converted to non-matter forms of energy, such as light; or kinetic and potential energy (example: heat). However, this conversion does not affect the total mass of systems, since the latter forms of non-matter energy still retain their mass through any such conversion. Today, conservation of energy refers to the conservation of the total system energy over time. This energy includes the energy associated with the rest mass of particles and all other forms of energy in the system. In addition the invariant mass of systems of particles (the mass of the system as seen in its center of mass inertial frame, such as the ...