modern physics 2007 trimester 3
  
    

	Monday, March 26	Tuesday, March 27	Wednesday, March 28	Thursday, March 29	Friday, March 30
class		last class until April 16	miniterm begins
what we'll do in class	we start dynamics (collision problems)
reading (always done before class)
in-class presentation	remember to have something ready.... some issues to think about if you have already done all the problems in the back of the book: does L(u/c) L(v/c) = L(w/c)? (can two successive lorentz transformations, first to a frame moving at v/c compared to the initial one, and then to a frame moving at speed u/c relative to the second one, be replaced by a single lorentz transformation to a frame moving at speed w/c ?  if so, what is w/c?  can w/c be figured out by multiplying the two matrices above?) [this would be analagous to our proof that R(j) R(q)  =  R (q + j)  from last friday] does L(u/c) L(v/c) = L(v/c) L(u/c) ? [as did   R(j) R(q) = R(q) R(f) ? does order of operation matter?]
written homework (by 5 pm)	the earth/rocket problem this problem is the culmination of our time dilation, length contraction, time-sequential picture problems of the first 3 weeks of the course... although i am encouraging those of you who have already shown mastery of  these problems on previous assignments to use the lorentz transformations procedures on this set, i am happy to have those who havent (yet shown mastery) use the old processes.... everyone really needs to get this problem perfect
lab
other

 

	Monday, March 19	Tuesday, March 20	Wednesday, March 21	Thursday, March 22	Friday, March 23
class			lab is now postponed we will spend all day in class trying to catch up yesterday we didnt get to talk about the yesterday's reading (relativistic velocity additions), so please make sure that you are on top of that for today's class
what we'll do in class	talk about the rotation of coordinates (see last friday)	rotational transformations, and their relevance to the lorentz transformations.... why the distance between two objects in three-space does not depend on the coordinate system	how to do relativistic velocity addition problems	organize the formulas we are supposed to be using for mass, momentum, kinetic energy, etc. for non-moving particles, for moving particles with mass, and for particles moving at light speed	figure out how energy and momentum transform understand where the formula for relativistic mass (gm) comes from
reading (always done before class)	1(6) up through the exercise 2 on the top of page 28: on the Lorentz transformations be able to explain in class exactly how the time dilation equation and the length contraction equation that we have been using to do our homework porblems follow from the lorentz transformations	pp 28-30 on the velocity transformations be able to explain in class exactly how the time dilation equation and the length contraction equation that we have been using to do our homework porblems follow from the lorentz transformations (yes, we will review what we did in class yesterday, just to make sure everybody got it)	again, pp 28-30 on the velocity transformations	pp. 34 - top of 37 know what the transformed mass, kinetic energy, and rest energy look like and how Serway came up with them... was he concinving?	pp 31- top of p. 34 plus the example they refer you to for proof of relativistic mass =  gm
in-class presentation		if a 2x2 matrix has elements a  b c  d what are the elements of its inverse?		find a matrix a) that reproduces the lorentz transformation equations b) that has an inverse equal to its transpose the column vector will contain  Dx (delta x) in one slot and something proportional to cDt (c times delta t) in the other slot	show that a rotation of  angle q (theta)  followed by a rotation of angle j (phi) -- i.e., R(j) R(q) -- is equivalent to a single rotation of  q + j, i.e., R (q + j)
written homework (by 5 pm)	the time dilation cartoon: using the info given in cartoon video, 1) find v/c by doing a time dilation problem 2) find v/c by doing a relativistic doppler shift problem (ignore anything else i may have said in class about this homework)		now due thursday: written and turned in: 1) 1(21) 2) (since no one showed this in class as I had hoped) for the muon problem (muon is created; muon reaches earth), calculate  the quantity: (Dx)2 -  (cDt)2 in both frames (earth and muon) and show that it is the same; you will have to re-calculate some of the quantities to more than the 2 or 3 significant figures we used in class; in any case, collect all of the data [Dx, Dt, and (Dx)2 -  (cDt)2] in a 2-column table (as we did in class) as part of what you turn in consider the lifetime of the muon (acc to muon); the cloud-ground distance (in the earth frame) and g (gamma) factor to be of infinite precision (how many significant figures will you need to use for the calculated quantities?  5? 6? 7? )	if you didn't get the second Tonya and Reid problem (which proves length contraction) virtually perfect (within 2 points), re-do it and show it to me in person by 4:30 pm today (this is the homework of 3/12/07)	1(56 and 20) monday's homework: the earth/rocket problem
lab			lab E1 due
other					pick up the 3rd edition of the book!

 

	Monday, March 12	Tuesday, March 13	Wednesday, March 14	Thursday, March 15	Friday, March 16
class				block D: not to hand in, but to bring to class today: suppose we have two different coordinates with coincident origins, but whose respective axes are rotated relative to each other by an angle q (theta); refer to diagram on drew on the board in class tuesday find an expression for each of the  coordinates in the rotated frame (x-bar, y-bar) in terms of the  coordinates of the first frame (x, y) and q block C is not ready for this, because they are still having trouble with muon lifetimes, so they need to bring to class today ON PAPER:   1) the lifetime of each muon (fast and slow) according to each observer (fast and slow muon) 2) a statement about which muon dies first according to each of the muons I will check; if you know you're going to be absent, make sure you turn this in to my box before class, so you get credit	block C: not to hand in, but to bring to class today: suppose we have two different coordinates with coincident origins, but whose respective axes are rotated relative to each other by an angle q (theta); refer to diagram on drew on the board in class tuesday
what we'll do in class			lab E1 need calculator and calculator knowledge: read lab	block D continues with doppler effect; Beck will tell us the egregious mistake; we have already addressed the  egregious inconsistency block C has yet to start this; hopefully they will have found the mistake and inconsistency also
reading (always done before class)		length contraction: pp. 18-20 (this was supposed to be for yesterday) relativistic doppler effect (pp. 22-24); look for an egregious mistake and a glaring inconsistency	read lab guide (and tape into lab book on the inside front and back covers)	block C: relativistic doppler effect (pp. 22-24); look for an egregious mistake and a glaring inconsistency block D: twin paradox (pp. 20-21)	twin paradox (pp. 20-21)
in-class presentation
written homework (by 5 pm)	1(13) & remember: no numbers until the absolute last line of the problem.... and remember to solve for v/c, NOT v the return of Tonya and Reid: now Tonya stands at the back of the train, where the light also is... consider the two events" 1) light leaves the back of the train 2) light returns to the back of the train Since you know the time between the two events according to Tonya, you can do a time dilation problem to find the time interval according to Reid; but Reid can also solve the problem by doing a d-v-a-t, even though he doesnt initially know the length of the train, according to him.  By equating the two method's answers, show that the train length according to Reid is g (gamma) times smaller than the length of train according to Tonya see the applet light_beam_clock.htm at T:\Student\kolena\Relativity_Physlets\ contents\s_relativity\sp_rel\ use the bottom light beam clock		1(51, 7) in # 51, remember to not use numbers till the very last line.... i would convert the distance given (in meters) to light seconds, of course (and remember, answers to odd problems are in the back of the boox		1(52, 15) in addition, for 15, calculate a numerical answer for qo (theta-sub-zero) if v/c = 0.95 and  q (theta) = 30 degrees
lab			we do our first lab, so make sure you have a lab book for today; your canary lab guide sheets should be taped in
other		doppler effect applet