midterm_prob1

midterm_prob1 - Midterm, MAE 120, Spring 2009, Name: 2: Z 2...

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Unformatted text preview: Midterm, MAE 120, Spring 2009, Name: 2: Z 2 ‘24: (20) 1. For full credit, he sure to use complete sentences for those questions that requlre d , narrative answers. Some helpful equations can be found in the Equations section. (If you on t recall the answer immediately, it is generally a good idea to move on and then return to the unanswered question after you have finished the rest of the test.) (4) 1a. What are the two main goals that motivate the study of heat transf r? I frieze mam 9 flea-.2” r5 5939 demmxu a; mil)»: Q JVW fl”? {mar/é garb? zs‘ Qév dgfiwzm/M @flmfira (Jasqzhévq/W féfb’w ism @wMaQé/M.Mfl £4 (4) 1b. Define the term isotherm and provide a proof using appropriate equations that heat flux must be perpendicular to isotherms. .414 1'me (5 6c il/M M Andras: cf p059; M @536 Q’e-rw/Qwaflgme 5W A4 elf/$047 flewsz‘céa: W [519%“IM 49a fit I (we #9 ('MA% gyaél’w m 9/1 haw M» 24/ 944/ wwmfl c219 ‘% a 3:1 Mg 44:! fiMfif'S/D My: gym-91‘ W7 ' a 24 Ari-lg rm ,3 a. _, or or '4 i5 5K5?! +53%“ “’“kasi {311w M 50% 92W :9: ’3 dad-29mg Gina/me. 294W?)- “$530 (4) 1o Assume that the axial temperature distribution, the}, for a rectangular tin of width, w, thickness, I, and ieagth, L, is known. Describe, using complete sentences and using equations as an aid, two approaches that can be used to determine the heat transfer from the fin. (We do want to see computing equations in your narrative that involve Tat/l.) 5/5445 WW.) /9 ,réHfl-tcflq gas-ad a“: 'JA‘LZ .xfa‘ufl AoaaK-é'g "Amp/sz »mua¢ (99m %flaa3,4fl gig flat 3:? 5&3” 3' iii—L39 r Alwwagflfvééc aid (2‘44! MQ'e7mfia 81/20}: (ML m J6 {Md/lei? Q0“: 24 52' flzfimflu is” = ftp/2w ~ was -+- awed 2571) as) Midterm, MAE 120, Spring 2009, Name: Zflfi'fl (4) 1d. What is the physical interpretation of the Biol number and the mathematical implication of low and high values of the Biot number? - ' . is 3.. (Mu 7” 3"” / P’fitfiy rte/m a5 ave ,. ; ¢ :5 .3418 Hf -\ 3 J Ca 5’, Bo r: .75; " 24—2 . E—gga PM Beet-’0) W 6289va TIMI—TTQQ wig/4 4m 5525' (4) 16. Using complete sentences, what is the meaning of the term, fin efficiency? What is the range of possible values? For a rectanguiar tin of constant cross-section ('14,; = Aw = wot where w is the width and r is the thickness) and for the infinite tip condition, under what conditions will the efficiency be high? Recall that r 4: w for the fin effectiveness to be high. art fé-QOA 0/92 5996M M r J!) % 2956 was 30%; 64W, aegis Q4» max/mum i049 5-92 [fly 39:9 draws /MM WW W up anti/{act 3 5; h A; 5 gram) «739) HW (2,)“ Wfifi pesslb/v? Wrin 15 0 71-22), @qummztflg W!- éflMzgaM 429M 4% ‘71:? I ‘74"! [if-{1014? :3, mg. nfi‘ifl 51$: 80- .=' ‘ first" .L-j/zr 1:7 71C lap-l '— L gagwt— ...
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midterm_prob1 - Midterm, MAE 120, Spring 2009, Name: 2: Z 2...

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