E= mc^2 question (1 Viewer)

[namburger]

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]

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

 

[advanced sam]

what????

 

[xiao1985]

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]

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

 

[kooltrainer]

no one can do it?

 

[gurusson]

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.

 

[samwell]

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.

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