Are the laws wrong????????? (1 Viewer)

[benthejack]

the conservation of energy principal states that energy cannot be created or destroyed right??
I came accross a question in an old physics exam (while practising for the real one)
which went as follows:
Deuterium and Tritium nuclei may fuse together as, as illistrated in the equation below.
2,1,H (ie mass 2 atomic no 1) + 3,1,H ----> 4,2,He + 1,0,n

The masses involved are:
mass of duterium = 3.34250*10^-27
mass of tritium = 5.00573*10^-27
mass of helium = 6.62609*10^-27
mass of neutron = 1.67438*10^-27

show that the amount of energy released in the above reaction is 4.30*10^-12 J.

the answer was this : E=mc^2 m= (3.34520*10^-27 + 5.00573*10^-27)-(6.62609*10^-27 + 1.67438*10^-27) = 4.77*10^-29

E=4.77*10^-29 * (3.00*10^8)^2 --> (3.00*10^8 = speed of light)
= 4.30*10^-12

basically what i understand from this is that mass is lost and that lost mass is turned into energy..... creating energy???
am i missing somthing or is the conservation of energy law wrong?
cos it seems to me like this reaction is creating energy............

 

[withoutaface]

the conservation of energy principal states that energy cannot be created or destroyed right??
I came accross a question in an old physics exam (while practising for the real one)
which went as follows:
Deuterium and Tritium nuclei may fuse together as, as illistrated in the equation below.
2,1,H (ie mass 2 atomic no 1) + 3,1,H ----> 4,2,He + 1,0,n

The masses involved are:
mass of duterium = 3.34250*10^-27
mass of tritium = 5.00573*10^-27
mass of helium = 6.62609*10^-27
mass of neutron = 1.67438*10^-27

show that the amount of energy released in the above reaction is 4.30*10^-12 J.

the answer was this : E=mc^2 m= (3.34520*10^-27 + 5.00573*10^-27)-(6.62609*10^-27 + 1.67438*10^-27) = 4.77*10^-29

E=4.77*10^-29 * (3.00*10^8)^2 --> (3.00*10^8 = speed of light)
= 4.30*10^-12

basically what i understand from this is that mass is lost and that lost mass is turned into energy..... creating energy???
am i missing somthing or is the conservation of energy law wrong?
cos it seems to me like this reaction is creating energy............

Yes the law of conservation of energy can be broken under certain conditions, specifically nuclear reactions.

 

[Xayma]

Energy and mass are equivalent according to E=mc²

Hence it is more the Law of Conservation of Mass and Energy where the total mass and energy is a constant (where E=mc²)

 

[Budz]

The energy 'produced' in this reaction is due to the unstable nature of the atoms. This can be defined as stored energy, the mass of an object is also related to energy, the speed at which the mass is being expelled is so great it is turned to energy,
This concept is similar to how can all the universe be condensed into a particle the size of an atom, the explosion 'big bang' caused such energy it was converted to mass..
Also einstein believed it was impossible for a mass to reach the speed of light beacuse as the mass approached the speed the mass is reduced to energy, so the mass would constantly decrease hence maing it impossible to reach such a speed...
So basically
stored enrgy -----> heat

 

[Xayma]

Umm it is the other way round, a lighter mass would make it easier.

The energy is converted to mass as speed increases.

 

[Assasinator_2]

As others have said, internal energy of the bonds holding the rather unstable atom together. At least that's the confusion that i can gather from your post.

 

[acmilan]

You learn about this if you do the option topic "From Quanta to Quarks" and you are actually asked to calculate the energy released, mass defect etc. This type of question was present in this years HSC

 

[JamiL]

no they are not broken ever, just that matter and energy are in essance the same thing. i.e matter can turn into energy n vise versa sown by the equation E=mc^2 c is constant therefore E is proportional to m. ie the law of conservation of energy n matter are the same thing.

 

[(^o^)]

hmm who is right who is wrong here?

 

[withoutaface]

no they are not broken ever, just that matter and energy are in essance the same thing. i.e matter can turn into energy n vise versa sown by the equation E=mc^2 c is constant therefore E is proportional to m. ie the law of conservation of energy n matter are the same thing.

Just because they can be transformed into one another does not mean that they are the same thing. I have milk and can turn it into butter, does this mean that milk and butter are the same thing? No. The Law of Conservation of Energy and Law of Conservation of Matter when considered as independent of one another are most certainly broken, it is only when we combine them into a single Law of Conservation of Energy and Matter that they remain unbroken under all (known) circumstances.

 

[Xayma]

Depends on if you follow string theory.

In which case matter is just a bunch of vibrating strings of energy

 

[Trefoil]

it is only when we combine them into a single Law of Conservation of Energy and Matter that they remain unbroken under all (known) circumstances.

I would suggest, then, that you take a look at some things called virtual particles, which by their very name should tell of things to come.

 

[M-turkey]

Energy is released and mass is lost.

This was discovered through experiements involving the atomic bomb.

The starting mass (uranium sp? etc) is greater than the mass of whatever is leftover in an explosion of a atomic bomb.

Therefore there is the great energy released

I think thats what happens.... can anyone confirm?

 

[Xayma]

It was discovered before hand although atomic energy was the first practical demonstration where more energy was gained then used to "encourage" the atoms to form/split.

 

[JamiL]

Just because they can be transformed into one another does not mean that they are the same thing. I have milk and can turn it into butter, does this mean that milk and butter are the same thing? No. The Law of Conservation of Energy and Law of Conservation of Matter when considered as independent of one another are most certainly broken, it is only when we combine them into a single Law of Conservation of Energy and Matter that they remain unbroken under all (known) circumstances.

Law of Conservation of Energy, and Law of Conservation of Matter have been dependent on each other i.e we now have Law of Conservation of Energy/Matter, which tells us that matter/energy cannot be distroyed or created but can be changes in form... i.e Energy ie light energy as a wave contains photons and a partical contains photons....
everything can be broken down to sub sub (sub) atomic particals, and hence were why i said in essence they are the same. just like...
ice and water are the same, or water vapor and ice. they are chemicaly the same but are physicaly different

 

[funking_you]

The concept at play here is one of the most important laws today, and many people have stated differing opinions, and guess what,
Einstein himself spent a great deal of his life explaining his most famous equation

What Einstein showed via his now famous equation was that mass and energy are in fact the same thing. Converting one into the other doesn’t therefore violate either of the two conservation laws. Both quantities are conserved, although the state of the mass/energy may have changed.

The following are Einstein's own words, in reply to a question not dissimilar to that which started this thread.

"It followed from the special theory of relativity that mass and energy are both but different manifestations of the same thing - a somewhat unfamiliar conception for the average mind. Furthermore, the equation E is equal to mc², in which energy is put equal to mass, multiplied with the [by the] square of the velocity of light, showed that very small amounts of mass may be converted into a very large amount of energy and vice versa. The mass and energy were in fact equivalent, according to the formula mentioned before [E = mc²]. This was demonstrated by Cockcroft and Walton in 1932, experimentally."

Its pretty hard to argue against a notion of the conservation law being 'violated', when that would be arguing against the great man himself.


Cheers,
George

p.s. 2005 is the Centenary of his greatest works, including this famous equation.

 

[clonestar]

All calculations are correct.

Einstein said that mass and energy are equivalent and therefore this decrease in mass is converted into energy.

This way the conservation of energy still applies as:

loss of mass is converted into energy, thereby allowing conservation to exist


CLONESTAR