exam1solutions

exam1solutions - PHYS4125 Fall 2011 Exam 1[Schroeder Ch...

Info icon This preview shows pages 1–5. Sign up to view the full content.

View Full Document Right Arrow Icon
Image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 2
Image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 4
Image of page 5
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: PHYS4125 Fall 2011 Exam 1 [Schroeder Ch. 1—21 Name Kat}? Z 2/18/11 There are 4 roblerns. Answer all 4 to the best of your ability. 1. (25 points) A Diesel engine requires no spark plug. instead, the air in the cylinder is compressed. so highly that the fuel ignites spontaneously when sprayed into the cylinder. 3) If the air is initially at room temperature (taken as T0=300 K) and then is compressed adiabatically by a factor of 15, what temperature is attained (before fuel injection)? Note: for air take the number of degrees of freedom to be S. a 56...} a mu .1... Wm ammo. 7‘7 Tf/ay V 9/75 . -1 7L3. 6' 'T‘ z - . Tag-9% .+\/\ r” 3 00 ‘f V; / 7—7} V; W V: fi 3cok( é‘Yf 936K b.) By what factor does the pressure increase? ‘FUF Q’Yl {Jail 2&3 (inch/3.0m; con OLJICLACL'J‘VQ Co/MPAwr‘m {Ci—3 ?‘ 'PVY: Cwafl one I"); ; EEC/0 3’ LAC-HA 3/: 7L 2—3; W c.) Calculate the work done on the gas, the heat added to the gas, and the change in internal energy of the gas during the compression. Express your answer in terms of N, To, and k3. USN? +1.9 15+ Leno AU -: Q + o) amé We idea 44/wa adfotba'hk ' , P“ mg” an5 G2 :0 A—U— : LA 5 _ (Pcfv U) "H“ ‘ ’7— / am; E%B’;i£yfl:?vg:cmood LL): "yCmS'F &V§:_éow5+[%3\é V +6 vb‘ x -1 l , J“ Y 7 w: ”cm—r (9’45 Tar—u Iva : fl (1 w 4,!) (3:4) V; V65” Y a 35% V0 - VX 7L? 6/ Kb)” ._————-’ f: —' D 1 ~ ,1 V2) ”‘V0 X4 V4 3”: f9] - EH LEM 7 7‘" Va Y My "PM, a 0/" [Istpiflzr “Wei? ” T: (W ° ' b”) v0 2. (20 points) Oxygen gas (02) is contained in a one-liter flask at atmospheric pressure and a temperature of 300° K 3) Approximately how many collisions per second are made by any one molecule, with the other molecules? oewmcswwam \7 /2: We 43:th Wmmm £5M gyms/A @ Mews ' igl— —— 1 (5e l): ,Q .2 m : Jig“ ' [IUFJD Mfr“? o 3 . r We FA) 35 F: .5}- ’5__l_._— : 1.0135616 1°C? : 9.146XIODI/m3 / V k3?” Libs/mo“ ‘7: Book a _ as; “4/5 ‘ m _. a mQ : Baflmu —— €311 XIO~JQE2 ON Wm :- 5.7‘l‘gl0cyf’ b) How many molecules strike one square centimeter of the surface of the flask, per second? Tasmmw/auorwag/AEMV; M M lama/U? r» Afl~fifems I a fill/61E moluufleo C: )0an .3}? 13% 'xO-{Uéms 3. (25 points) An otherwise empty room contains 6X1026 air molecules. ,3) How many times more probable is it to have them split exactly 50-50 between front and back halves of the room then. to have a 49—51 split? but BMW/ml dish; L (147?“ fir “Ms A lee Wm - . N l ’1’ PP I « ”/61 ‘ ' “’3 ”m 3359’ 1 yam-yaw. a: -M 2: fr”? $‘fi/6‘f {-W/a— Wt? ab (IAN)! WM. Him/m : MW)! + New. ”D M” ,%1hvg —~ aid/l 4.65”] [ho-5H!" on“, 9 _ (In >533; 61m} Mow - My“ - Olt‘mlnorZ/fl}+6.5"NlV105’U " " N 1” VA Pol M p cmé calm: ”7/9 — I acme” a [go/m so I Pas/s: the most probable 50—50 split? . L3. 0253? : m 31'31’5‘0 L3. 4.7; O— -- w : HOS/“(O TERM SWM lewfifl‘w T: - 3 (wag l -[( ‘75 * Vila/@031 OR Pan/5‘0 : fig— 6 W” fie C I 7, ”if/3.731%?” @ — [Q (L0 _ [mask/1096 -3.oouo"€3 /g ( 1.325100“) 3‘ '56 W34? afl?”((0% W M \l 4 _ 79a m no“ SW“) :C 3M 4. (30 points) Show that the multiplicity of a two state paramagnet in the limit of low temperature can be approximated to be .Q=(Ne IN 1)“ where N l is the number of dipoles that point downward. You will find it useful to start with a binomial distribution, calculate 111(0) , make use of the Stirling approximation for the factorials and the approximation ln(1+x)~x 4} “NJ?— é: N \Y} H ‘- 6‘)’ “all“ (N’UQA ‘- NM \WUJ/ SW02 V¢3Mawv In); N pm; — m— Histami— 5‘}qu - or, mu ...
View Full Document

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern