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E= mc^2 question (1 Viewer)

namburger

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A piece of radioactive material of mass 2.5 kg undergoes radioactive decay/ how much enery is released if 10 grams of this mass are converted to energy during the decay process

Is the answer a simple E = 0.01 x c^2
 

kooltrainer

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oh! what a noob nam .. noob question!xD
E = 0.01 x c^2
finish !*
 
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xiao1985

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Now here's something for you nerds to think about:

E has the unit of J

m has the unit of kg
c has the unit of m/s

so mc^2 has the unit of kg m^2 /s^2
which also has the unit of J?!?!

Does this sound right?
 

namburger

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xiao1985 said:
Now here's something for you nerds to think about:

E has the unit of J

m has the unit of kg
c has the unit of m/s

so mc^2 has the unit of kg m^2 /s^2
which also has the unit of J?!?!

Does this sound right?
From Wikipedia:


The newton is the unit of force in the SI system; it is equal to the amount of force required to give a mass of one kilogram an acceleration of one metre per second squared. Algebraically:


One joule is the work done, or energy expended, by a force of one newton moving one metre along the direction of the force


Therefore
 

gurusson

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kooltrainer said:
oh! what a noob nam .. noob question!xD
E = 0.01 x c^2
finish !*
i am pretty sure u a right, i did a study into this in year three (nerd i no) and that was the conclusion i came 2. my friend who is a particle physisist sed that this is essentially right, he wouldn't tell me wat was wrong tho.:jedi:
 

samwell

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gurusson said:
i am pretty sure u a right, i did a study into this in year three (nerd i no) and that was the conclusion i came 2. my friend who is a particle physisist sed that this is essentially right, he wouldn't tell me wat was wrong tho.:jedi:
The only thing that seems wrong in the mathematical process is we are taking 10g as the rest mass. But if u consider the rest mass as 2.5kg and the rest energy as 2.5kg*c^2=rest Energy and the change in mass in 10g so the new energy of the new mass is given by E=(2.5-0.01)kg*c^2 there fore the energy emmited is the difference btn the initial and final. I think the answer from 0.01*c^2 is right but it doesnt take into account the essential differences between whats the rest mass and the change in mass. Am pretty sure 0.01*c^2 would the marks though
 

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