Energy

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__//Definitions//__

 * Energy** is a scalar physical quantity that is a property of objects and systems which is conserved by nature. Energy is often defined as the ability to do work.


 * Work** is the quantity of energy transferred from one system to another without an accompanying transfer of entropy.

Energy is neither created or destroyed. - Kenny - Energy is also conserved in a system, but only an isolated system - kboyk - But Energy is converted from one form to another. -danwisniewski

The capacity for doing work as measured by the capability of doing work (potential energy) or the conversion of this capability to motion (kinetic energy). Energy has several forms, some of which are easily convertible and can be changed to another form useful for work

The capability of doing work; different forms of energy can be converted to other forms, but the total amount of energy remains the same. - Matt

Conservation of Energy is also called the First Law of Thermodynamics. Energy is conserved, it is neither created nor destroyed.The total amount of energy in a system stays constant and can't be recreated it only changes forms.-AEdenburg2

The conservation of energy is a consequence of the fact that all laws of physics (including the values of the physical constants) are invariant under translation through time; they do not change as time passes.-danwisniewski

Although the total energy of a system does not change with time, its value may depend on the frame of reference. For example, a seated passenger in a moving airplane has zero kinetic energy relative to the airplane, but nonzero kinetic energy relative to the earth.-danwisniewski

All living organisms require an external source of energy to grow and reproduce. -lfabia

Several different forms of energy, include kinetic, potential, thermal, gravitational, elastic, electromagnetic, chemical, nuclear and mass. kinetic energy- //the work// //needed to accelerate a body of a given mass from rest to its current velocity// kboyk potential energy - energy stored within a physical system kboyk

The methods for the measurement of energy often deploy methods for the measurement of still more fundamental concepts of science, namely mass, distance, radiation, temperature, time, electric charge and electric current.

Potential energy, symbols //E//p, //V// or //Φ//, is defined as the work done //against a given force// in changing the position of an object with respect to a reference position.

Energy is used in chemistry, biology, geology, and astronomy (among others) it is used to explain many of nature's phenomena! - lridgeway

--**Units**: ergs, calories, joule --bcohn
 * Measurement**: There is no absolute measure of energy--energy is defined as the work that one system does on another. Only the transition of a system from one state into another can be defined and measured.

__//Pictures//__
These are types of energy! - yahoo ! - lridgeway --bcohn E is the rest mass energy, m is the mass, and c is the speed of light in a vacuum. Einstein found the equation...get it? Mass...energy...get out of bed...? --bcohn A Calorimeter is an instrument used by physicists to measure energy. In a roller coaster roller, at the top it has its greatest potential energy. As the cars go down they pick up speed and kenetic energy.They lose it again as they rise up the hill again and so on... -AEdenburg2 Any number of balls released from one side will release the same number of balls from the other side. As the outside ball reaches the others the potential energy is decreasing and the kenetic energy is increasing. In the middle the kenetic energy is at its maximum and the potential energy is at zero. When its on the other side, once again, the potential energy is at its maximum and the kenetic energy is at zero. -AEdenburg2

//__Examples out in the world, or real applications of Conservation of Energy__//
It is changed from one form of energy to the other. Energy from the sun is absorbed by vegetation which use it to grow (phosynthesis) and then animals eat the plants to get the energy and then people eat the animals to get the energy. unless theyre vegetarians. - EARUN.

__//Problems//__:
Which person is doing more work, a man holding a 500lbs. barbel over his head, a boy taking 100 lbs. up 5 flights of stairs, or or a car pulling 50lbs. at a constant rate over 10m.

A person taking 100lbs up 5 flights does the most work because his force times distance are greatest. awillcox

The person walking up 5 flights of stairs because he is going the farthest distance therefore doing more work. -Matt

The boy going up the stairs. Stairs are hard to go up. ;( -jarediscool

The boy taking 100lbs up the stairs because it takes more energy to go up and forward at the same time, and 5 flights is a farther distance than 10m that the car is pulling and the man isn't even moving, so therefore the boy is doing the most work. -gwang

__....................................................................................................................................................................................................__ Can something have energy without having momentum? Explain. No. because if the pbject is not moving or does is not doing any action, it cannot move. - rbambal Yes. A lightbulb has energy but doesn't have momentum. awillcox Yes, a battery has energy but no momentum. -lfabia Yes Potential energy is stored energy, not yet moving or "working," but it is still energy. - ebrobs Yes, because many things generate energy without moving anywhere like a battery. - Matt What about that potention energy stuff. If a ball is at the top of a hill, it has no momentum, but a lot of potention energy. amirite? -jarediscool Yes, batteries have energy and candles/fires have heat energy and all of them have no momentum. -gwang Yes. Since energy is not specifically defined in this question, it can be in different forms. Mentioned before, fire and candles have heat energy, and batteries generate energy. yahoo! - lridgeway

__....................................................................................................................................................................................................__ Can something have momentum without having energy? Defend your answer. Yes, because if a bottle, for example has weight but it does not have to be moving, thus does not have to have energy or do work. - rbambal No, because momentum is mass x velocity and velocity is distance/time so to have momentum something must go a distance. awillcox Yes. Since the ability to do work is energy and work is force x distance. Therefore, momentum must have force x distance in it. However momentum is mass x velocity or mass x distance/time and since force is equal to mass x acceleration, momentum does not have energy because it has no acceleration. Therefore, something can have momentum without having energy. -lfabia No because if it has momentum, it must have a velocity and be moving (because p=MV) which means it is doing work, so it must have energy. - errunb. I agree with Ann in that if an object has momentum it must be moving and therefor have energy. - Matt I guess that it would. If something has momentum, then what gave it that momentum? There had to be energy involved somewhere. -jarediscool No, because momentum= MV and since it needs velocity to be moving and to have momentum, there needs to be some form of energy to create the velocity which is necessary for momentum- gwang