modern physics 2009     trimester 3

Serway's Chapter 16 (on-line only) on Cosmology

course expectations   &   syllabus

April 27
April 28
April 29
April 30
May 1

(always done before class)
examples 13-10,11
on pages 490-491

14(1) and 14(4, first 2 pages)

on basics of nuclear fission
finish 14(4) and continue through page 516

read the lab, so you are prepared

things you should know the answer to before coming to class

what isotopes are used to date

a) the age of the earth (or other solar system objects)

b) the age of the oldest human bones

how/why C-14 dating works?  why that isotope?  how does C-14 get into things?

questions to know the answer to for class:

does a single uranium fission produce the kinetic energy announced in the book?
(a nice show/tell here)

why does the uranium fuel have to be enriched in some reactors?  how is the enrichment done?
(i.e., how is U-235 separated from the more abundant U-238)?  three methods -- all learned intro physics or chemistry should come to mind)!

why does a U-235 require a slow neutron for fission?
(you learned this in your first physics course!)

how do you slow neutrons down?
(you learned this in your first physics course!)
same questions as for wednesday

be prepared to answer a few in depth (using physics!)

(written assignments
to be turned in)

1) problem 7 from the relativistic collision handout

2) 13(54a,c)

1) problems 3 & 9 from the relativistic collision handout

2) 13(38)

1) problem 10 from the relativistic collision handout

web stuff

make sure that you have a rough value for the top quark mass (and the neutrino momentum -- speed and direction) for class today
(you can get back half of the points you lost friday
if you do)

lab E2 due today

top quark lab due

we do
lab E3  on radioactive decay

of the week

April 20
April 21
April 22

April 23
April 24

cyclotron applet

(always done before class)
review 13(5) up through example 13.8
(which we supposedly have already read)
the sections in 13(5) on beta decay (although temporarily ignore the section on carbon dating) and on gamma decay

also 15(2) on antiparticles, plus the short section on Leptons in 15(4)
pp. 560-561 on Baryon number and Lepton number
(this should have been part of your reading for yesterday)

reading for Thursday's lab:
the discovery of the top quark:
1) 15(9) on quarks
2) Essay beginning on page 590:
"How to find a top quark...."

this is difficult reading, so you may have to skim in places....
the schematic on page 594 is important

the reading is long, so please start early

you should have already done the reading in yesterday's slot...

read the top quark mass lab handout
13(4) on the radioactive decay laws.... a really important -- and fairly long -- section that will be the basis of our 3rd radioactivity lab next week

what equations are the basic ones of section 13(4), i.e., which are you allowed to start a problem with?

things you should know the answer to before coming to class

please do practice problems from the handout on relativistic collisions;
whatever isnt done in class by mid-next-week will be assigned for homework

(written assignments
to be turned in)

deadline for showing me your calculation of the v/c limit for which using the Newtonian version of KE makes a less-than-1% error.....
is tonight's tutorial....
don't wait till the very end!

13(51, 52)

in each case, the problem means to ask you to calculate the total kinetic energy released in the reaction

(as we discussed in class monday, remember that first the reaction must be written, then the conservation of charge, baryon number, lepton number, and only then conservation of mass-energy (which must include electron accounting)

you may want to wait until after class tuesday to start this, although you should be able to do on your own (especially if you've had astrophysics)

you will be expected to have the neutrino momentum (and energy) from the top quark lab done yesterday to present in class today
2 homework problems:

1) problem 13 from the relativistic collision handout


2) ...on the recent quiz, I claimed that a S+ would decay as

S+ --> n + p+

and I claimed speeds of 0.70c and 0.56c for the two decay products (in the center-of-mass frame).... I think I calculated these speeds incorrectly...
find the correct speeds....
masses are in your text, table on page 557
web stuff
go here to request a PDG to request the Particle Physics Booklet.... please do not request anything else.... since you are (probably) not on their mailing list, you will have to click on the appropriate link to give them your mailing address


start working on E2:

section 14(7) will be helpful in understanding how gamma rays interact with matter
(your first physics course should be helpful on how electric charges -- alpha and beta particles -- interact with other charges

section 14(7) assumes you have studied the phenomena (pair production, the photoelectric effect, the Compton effect) so you may have to go and read the sections on those phenomena also

of the week

April 6
April 7
April 8
April 9
April 10
 if you had an arranged absence last Friday, reading quiz (on Moodle)
due by 8 pm YESTERDAY

quiz today on

(chapters 1 - 2)
what we'll do
in class
details of alpha decay
and conservation laws

(always done
before class)
finish 13(2), an extremely important section, especially the end
[you might also read section 15(3), which has a better version]


13(5) up through example 13.8
only two more days left this week...
no presentation on quiz day nor lab day

(by 5 pm)
binding energy of a nucleus of YOUR choice

make sure that use obtain all masses from Appendix B

check to make sure  that your answer is consistent with fig 13.10

credit is somewhat dependent on how unique your calculation is
(it's inversely proportional to how many other people choose the same one as you)

only 1 problem because you are studying for the quiz, by doing problems out of the back of chapters 1 and 2

lab E2

which has a lengthy prelab , due at the  beginning of lab

web site for finding nuclei masses, half-lifes, etc.

type the nucleus you're interested in inside the box at upper left corner... for example if you want info about carbon-12, type C-12



  pages for march 2009