Mass-energy conservation in nuclear reactions

Click For Summary

Homework Help Overview

The discussion revolves around the conservation of mass-energy in nuclear reactions, specifically addressing discrepancies in calculated energy values related to reactants and products. Participants are exploring the implications of mass differences and energy transformations in the context of nuclear physics.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • Participants discuss the calculation of mass and energy using E=mc^2, question the relationship between initial and final masses and energies, and seek clarification on the application of conservation principles.

Discussion Status

The conversation is ongoing, with some participants suggesting that the original poster may not have applied the conservation of mass-energy correctly. There is an emphasis on showing work to identify potential errors, and the discussion is probing into the relationship between mass and kinetic energy in the context of the problem.

Contextual Notes

There is mention of specific energy values related to alpha-particles and the need to account for differences in mass between reactants and products, indicating potential assumptions or missing information in the original calculations.

voreryar
Messages
1
Reaction score
0
Homework Statement
If the energy of the incident alpha-particle is 7.68 MeV, calculate the kinetic energy of the proton assuming it gets 17/18 of the available kinetic energy
Relevant Equations
E = mc^2
viber_image_2023-05-29_16-46-06-465.jpg

I found the total mass of the reactants and the products, found the change in mass, used E=mc^2 and changed my answer from Joules to eV, but my answer is wrong. I'm guessing I have to do something with the energy of the alpha-particle given in the question

The answer is supposed to be: 6.58 MeV
 
Physics news on Phys.org
Did you notice that the total mass of the products is greater than the total mass of the reactants? How do you account for this?
 
Can you show your work?
 
voreryar said:
I found the total mass of the reactants and the products, found the change in mass, used E=mc^2 and changed my answer from Joules to eV, but my answer is wrong.
Hi @voreryar. Welcome to PF.

You need to show your working so we can spot any mistakes you have made. But it sounds like you haven’t applied conservation of mass-energy correctly.

voreryar said:
I'm guessing I have to do something with the energy of the alpha-particle given in the question
Good guess!
Initial total rest mass ##=m_i##.
Final total rest mass ##= m_f##.
Initial total kinetic energy of all particles ##= K_i##.
Final total kinetic energy of all particles ##= K_f##.

What is the relationship between ##m_i, m_f, K_i## and ##K_f## in this problem?
 

Similar threads

Replies
13
Views
1K
Replies
8
Views
5K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 28 ·
Replies
28
Views
2K
Replies
9
Views
6K
  • · Replies 4 ·
Replies
4
Views
836
  • · Replies 10 ·
Replies
10
Views
3K
  • · Replies 1 ·
Replies
1
Views
3K
Replies
1
Views
2K