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The relation between mass and energy (E = mc^2) is a consequence of Einstein's theory of special relativity. This theory is based on the empirical fact that the speed of light is constant for any non-accelerating observer.
Why does this lead to an equivalence between mass and energy?
Well, let us consider a thought experiment. Imagine there is an object A which emits two photons (particles of light), one to the right, and one to the left. Both photons have an equal amount of energy (e.g. E/2). Because both photons have the same energy, they also have the same momentum and the total momentum in the frame remains the same (the total energy also remains the same since A has lost E through the emission).
Now imagine what this looks like for an observer in constant (non zero) motion. According to special relativity the photon traveling in his direction is blue-shifted, thus having an energy greater than E/2. The other photon is instead red-shifted, having an energy of less than E/2.
Of course the total amount of energy combined is still E. However, since the photons have unequal energy they also have unequal momentum. Object A however does not change his velocity during emission (remember that in the rest frame (where A is not moving) the photons were emitted with equal momentum in opposite directions), so now there is a net momentum gain in the direction of our moving observer!
But momentum must be conserved! How is this possible? The answer is that object A DID lose momentum (exactly enough to cancel the extra one), but since its velocity did not change it must have been its mass that has changed! (Remember that momentum equals mass times velocity at low energy).
Calculations then show that the amount of mass lost to A is equal to E/c^2. Hence the equation E = mc^2.
In a sense, then, mass and energy are related because the speed of light is a constant!
Wiki User
∙ 12y ago
Mass and energy are interchangeable in accordance with Einstein's theory of relativity, expressed by the famous equation E=mc^2. This means that mass can be thought of as "condensed" or concentrated energy. When mass is converted into energy, or vice versa, the total amount of energy remains constant, illustrating the equivalence of the two.
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How is energy turned to mass What is an example of turning energy to mass?
Photosynthesis is an example of turning energy into mass. E=mc^2 is how energy is turned into mass.
Can energy converted into mass?
Yes. In a way, energy and mass are closely related; energy HAS mass, mass HAS energy. Energy gets converted into mass routinely in particle accelerators. The kinetic energy from the moving particles gets converted into new particles.
Can energy change into mass?
No. Energy has an ASSOCIATED mass. There is no such thing as mass-to-energy conversion, or energy-to-mass conversion. In a nuclear reaction, for example, BOTH mass and energy are CONSERVED. For a more detailed explanation, check the Wikipedia article on "binding energy".
Is the total mass and energy in the universe constantly changing?
The Law of conservation of mass-energy indicates that the mass-energy of the universe is constantly changing to maintain the mass-energy constant.
Does sound have mass?
No. Sound is mechanical energy. Mechanical energy does not have mass. And no form of energy has mass. But energy has a mass equivalent per E=mc2 thanks to Albert Einstein.
Is light mass or energy?
Um... yes? Light is a form of energy. Energy has mass.
How is matter and energy interrelated?
Mass "has" energy, energy "has" mass. The relation is: e = mc2.
When is mass converted into energy?
Mass and energy are equivalent, so there are exchanges of between mass and energy any time there is a change in motion (kinetic energy). But Atomic energy is the most familiar conversion of mass into energy. The explosion of an nuclear bomb, or the energy generated by a nuclear reactor are consequences of conversion of mass into energy. Energy from combustion is not primarily derived from mass/energy conversion, but from exothermic chemical reactions. In fact, any such exchange between mass and energy would operate in the other direction, as gasses gain mass as they are put into motion (increased kinetic energy=increased mass). But any such gain is so tiny as to be meaningless.
Can you convert energy into mass?
No. Mass and kinetic energy are not the same thing.
What do potential energy and kinetic energy have in common?
they have mass
Does thermal energy affect mass?
no it does not thermal energy has no affect on mass
How is mass converted into energy in nuclar fusion?
It isn't. This is a popular statement, but it is complete incorrect. Both mass and energy are conserved. Energy: The energy was already available previously, but in another form (nuclear energy, which is a type of potential energy). Mass: The heat or light that is produced is energy; it has an associated mass. For example, the photons (light) that leave the Sun not only take energy, but also mass, away from the Sun. This mass is exactly equal to the "missing" mass.
