Help with Exams This Week? Ask Bobster!

  • Thread starter Bobster
  • Start date
  • Tags
    Exams
In summary, the conversation is about a student asking for help with their university exams and a specific homework problem involving an inertial observer and the decay of a particle into two photons. The student provides their attempt at a solution and asks for confirmation or any further help. The conversation ends with someone suggesting to double check the dot product calculation.
  • #1
Bobster
16
0
Exams This Week...need Help Please !

hi guys ! good 2c every1 again..been a while..ive got my 3rd year uni exams..and it aint lookin good...can ne1 help me with this one ?

Homework Statement



An inertial observer sees a particle moving at a speed 3c/5..Its then seen to decay into 2 photons..draw an accurate diagram to illustrate the situation before and after the decay takes place.

What energies,expressed in terms of the rest mass energies of the initial particle would the observer measure for the 2 photons ?


Homework Equations



Using theory of conservation of 4 momentum/energy..maybe use of invariance of scalar product in any intertial frame..

The Attempt at a Solution



im ok with the diagram...its a line of form y [ct] = 5/3 x + C..right ? and then it splits into two 45 degree lines that correspond to worldlines for photons but in opposite directions at some time t...

now the 2nd bit...gamma is g =5/4 and v =3/5 c

i did P initial = P particle = (g 5/4 mc,g mv,0,0)=(g 5/4 mc,3/4 mc,0,0)

so taking dot product with itself i get -17/8 m^2 c^2

now i take a new frame..centre of momentum frame where its at rest the decays to two photons in opp directions...
here P final =(E tot/c,0,0,0) where e tot is total energy in this frame

so takin dot product wit itself and equating to above i get

0.5 root(17/8) E = E (tot) where E was rest mass energy of particle initially = m c^2 and E(tot)/2 gives energy of each photon in rest frame of initial particle...


can any1 help me ? is this right ?

cheers for any help

bobster
 
Physics news on Phys.org
  • #2
any ideas folks ?
 
  • #3
don't have comment on the first bit (i guess you can cross check that easily once you have got 2nd bit correct)
you method for the 2nd bit seems fine to me, but the dot product was evaluated incorrectly (or my calc was wrong instead) either way, u should double check. remember the metric for the dot product is either -+++ or +---.
 

1. How can Bobster help me with exams this week?

Bobster can provide you with study tips and strategies, help you create a study schedule, review your notes and materials, and offer practice exams to prepare you for your exams this week.

2. Is Bobster available for help at any time this week?

Yes, Bobster is available to help you with your exams this week. You can schedule a session with Bobster at a time that is convenient for you.

3. Can Bobster help with all subjects or only specific ones?

Bobster can help with a variety of subjects, including math, science, English, history, and more. However, it would be best to check with Bobster to see if he can provide assistance in a particular subject.

4. How can I schedule a session with Bobster?

You can schedule a session with Bobster by contacting him via email or phone. He will work with you to find a time that works for both of you.

5. Does Bobster have any qualifications or experience in helping with exams?

Yes, Bobster has a PhD in Education and has years of experience in tutoring and helping students prepare for exams. He is knowledgeable in various study techniques and is dedicated to helping students succeed in their exams.

Similar threads

  • Advanced Physics Homework Help
Replies
2
Views
590
  • Advanced Physics Homework Help
Replies
4
Views
268
  • Advanced Physics Homework Help
Replies
13
Views
1K
  • Advanced Physics Homework Help
Replies
10
Views
1K
  • Advanced Physics Homework Help
Replies
1
Views
2K
  • Advanced Physics Homework Help
Replies
31
Views
4K
  • Advanced Physics Homework Help
Replies
5
Views
2K
  • Advanced Physics Homework Help
Replies
2
Views
1K
Replies
2
Views
944
  • Advanced Physics Homework Help
Replies
6
Views
3K
Back
Top