ef157-lec-1-9-mu-h

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The University of Tennessee, Knoxville *

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157

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Aerospace Engineering

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Oct 30, 2023

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pdf

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Announcements — Upcoming Deadlines = Monday m [hursday o No RQ o Proj 2 Update and o Class Activity Problem Statement o OLHW 1.8 m Friday s [uesday n RQ2.2 o Exam 1 o PHW 1.8 s Wednesday 0 RQ 2.1 o Perspective seminar 5:30- 6:30 (Mechanical) Exam 1 — Tuesday, Sept. 17® m Covers Module 1 s Five Problems o 2 short (15 points), 2 medium (20 pts), 1 long (30 pts) o Plus a bonus (5 points) m You can bring one sheet of notes (i.e., a “cheat sheet”) Must be on Engineering paper Front side ONLY = We, don'+ fpvov}d*%S In YOUR handwriting €0uononS SE;N‘* o M~ Put your name at top ijfiowwna*‘ hat X Anything you want to write \3 You are to turn it in with the exam NO other books, notes, etc. are allowed = We will provide Constants and Conversions — see Canvas s Bring your own calculator , Uy o res hrckans L 0O 0 o0 o0 o0 .

Tips tor Preparing for Exam 1 s Review and summarize content (lectures, PHW, OLHW) o MAKE YOUR NOTE SHEET m Study material you are least confident with o Write material o Check for understanding o Work problems o Ask questions m Pull at least one old exam to work through as practice o ldentify the topic the question is testing Time Estimates 15 pt — 11 minutes o Use good problem solving strategies o Use your note sheet | o Work under the time limit 20 pt — 15 minutes = Take breaks and get sleep!! 30 pt — 22 minutes | Cognition — Problem Solving So what happens when we try to solve a problem? A IOt' ' SHORT LONG SENSORY TERM TERM MEMORY MEMORY| » F"‘If“ ‘WORKBENCH’ P , - 1y 7 o - | 'NPUTSTREAM _i b ®© @)P ,i°_1 4 - e 1 | ® _ e s a . A ® s A - 3 —J?‘:‘E “ . i'o)og q : [ --‘on ] < k b ® - A Qté . 2 - ¢©;\ B EXECUTIVE %f 1 , E , CONTROLLER X . OUTPUT @{i % D ‘ \'\_.’u{) > —

So what do we do... Cognitive Load Theory Our brains cannot process infinite amounts of information at a time. I d by th in which . I o . AN irformation s presented. Problem Solving information is presented INTRINSIC CL ' Imposed by the learning task Process!! | GERMANE CL Devoted to processing information | ' and constructing schema 081127882 "’[381 127882 CHUNKINé | Test Taking Tips s ldentify concepts being tested o Start with the problem you know you can get right m Write stuff down o Givens o Unknowns o Equations o Diagram oy ot S v\‘of pnt m |f you get stuck, move on — o+ Yo “ i alSo 3] » Take a deep breath! i R S A

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What we expect to see s Coordinate system o Include u@ when needed o Don’t forget your datum < 2e+© m Base equations s Enough work that we can follow what you did m Boxed answers s USC ans. = Appropriate units = ¢ ,T»Wf'%; cjio o«’wg:—;c‘fc e . . : . \\ Ao o Watch unit conversions and unit consistency wt *¢ -\:b W s Magnitude and direction for any vector o Correct vector notation ‘ Topic Outline m Statistics o Mean, Median, Mode, Range, CV, Standard Dev. m Units m Sig Figs s General Kinematics (both linear and angular) o Distance vs. Displacement o Velocity vs. Speed o Acceleration m Vector Kinematics s Relative motion m Pulleys and Gears m Constant Acceleration Kinematics

Don’t forget about... e N e € “oud = Gears e ’V“‘;ams s Angular kinematics Vi For practice look at OLHW and PHW Constrained Motion — Connected Bodies * Blocks A and B cannot move independently of each other. * Single degree-of-freedom system * Only one independent body position @ O, @ ligl lley syswm, E Pulleysystem 3 Mhe odistanct P ™oves pp 8 olwvided over all Seamunts otrackhed O R =9 -Furupz +33 B doesn hnove ls for Need to establish Kinematic Relationships (position, velocity, acceleration) between the various connected bodies. 10

Also, check out supplement on Canvas. Pulleys # of Units A moves # of Units B moves o\ J A 11 m d = tooth spacing m N = number of teeth gears in direct contact rotate in opposite directions I\GTARA o _wBRB] g m d, must = dg for proper meshing 12

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Angular Kinematic Constraint - Gears Kinematic constraint || ™ (UANA — _wBNB O AHANA — _AHBNB ‘I aANA — —CZRNR / S el 13 : : . \ ‘ Relative motion Wattm e oo @\. . o hein e lpfo ) Ao e Define your reference frame of 4 0 et om The motion of B relative to A is the motion of B relative to “ground” minus the motion of A relative to “ground.” ]| ey 1s T — _ = = \ . | - rB/A T rB rA wswt@\q ok Y}vldu < . I _ J(\f\a\—"‘ VB/A o VB VA AV 9\%;:;\ Ap,4 = dp — Ay ™ L . .y = - o oo P N Check out resources on Canvas 14

Constant Acceleration S=S0+U0t+5at2 v=vy+at v?=v5+2a(s—sy) 2 «9=6’0+a)0t+a% w=w,tat a)2=a)5+2a(0-¢90) - OW have (0‘}'\/\07\«6)0 SCer~a~03 < \r\/\u\‘\\v\b s Read problem carefully NG m Use the problem solving process m Practice! ng O~ UL O\~ o 15 | Let’s solve some problems \/\/r\g\n bou j‘,@—\' stuone ol hese S—b\v S & m Use the problem solving process!! o Conceptualize the problem in your own words |dentify given values Draw representation Write what you are being asked to find ldentify concept being tested Select appropriate equations and write them down s If you don’'t know where to start then start with an equation that has the variable you are asked to find m Focus on the set-up cC O o 0O O 16

2) (15 pts) Dr. Kit designed a rack with a pulley system in his garage so he could easily store his bicycle when not in use. In J his system, the horizontal bar that connects Pulley A and S Pulley B always remains horizontal and parallel to the ground and ceiling. That is, Pulley A and Pulley B move in unison in the vertical direction. This way, the bicycle does not \\t‘\ tilt forward or backward as it is being raised or lowered. If the v \b‘J\ bicycle is mmally at rest and Dr. Kit accelerates the rope at C at o & a rate f 0.75 fi/s” downward as shown in the figure, calculate a the velocity and acceleration of the bicycle after 2.5 seconds. S\no«,v 4+ A xNe K\wwmc Q<7uaA\dV\S OST\/ BSp -+ NB&S\} NebSe Musd Laleel T Osrhons <+ \\om a CS =0 @ | =conslont= C + L FL -\L S ASaz AN ke L indenws of sb,SB gc Y;/\US‘" "\"’\"\j NA'* Ng) DSA — NCB%C = 0O L‘ - SA—\-C \_._‘*:: g%_y C =S5 C LezSs.~C a’{ :> L}b\/)\__ />VC: O ’\7|\/ WA U Waw%a/\ L= Qe @) s (gm0 (Ser O (SevCh e \D o~ =) Lf/BO\ S =0 Oo»«n\?\,$ VOvn:oLe,s \ L= 2Sp*2@g"" SCS\"CG\?S"‘S&W\-}I %\, -\—\' K\NW\“‘-\CS QV( S)o( S = | = I_\.SF S Q'-C. U\\ aglve Ve W Nt bmaicS Trom Tante you 4w oo\ e —\—‘aiuse—‘?u\?) %SWZ) U Vo L use VA= Va,3pt Ew 3) (20 pts) The current of a nver causes a floating ball B to move a constant speed of 4.6 mi/hr duc south. Additionally, a wind causes the ball to move N K a constant speed of 3.1 ft/s on a beaning of 35° cast of north. a) Determin the velocity of the ball with respect fo Observer A who is YC\Q“‘\‘L standing still on the bank of the river. Q\ao»’*-z b) Determine the velecity of the ball sith respect to Observer € who is W walking over a bndge duc west at 2.8 mivhr. \ Yoovdna IS a Wi L = Wwnte Your i W ova§, Srart+ L) W ens o T 5 ~ oM~ OWn S \ru,\;\-.s‘v\ S Ve = (07 -Ulmilhe | | "/ - C \/I/$“r\ok= ( 2 o194 SIS T + 2 .1dd c@s?>§c:/)\) M\]L\r‘ (—k (\Z‘TA-\Q'S"\W\'\W\ I Now, Lavwe 6 What Lou are a sked Lor I 0‘\ Velc c of pa\l 1etakve o A Lohick s San~e KS\, n~L &S —M~y S/UV\"*O\ . ‘e plug = _y New st vy — — " N b v N e current =ije > 3 g < N

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motorcycle start from rest at Mal Suvc 4) (20 pts) A carand a V,=O ~—, %50 A2Rne %S W | . .. the same time on a straight track, but the motorcycle is "y 2 C,GY‘Q 25.0 m behind the car. The /,///“ﬂj > d-)" caraccclcratcsatag@v - o ¢ rate of 3.70 m/s? andThe Star .- S - > i i - 3. 2 e <« oradoms = < SFomgs “ wWha i a) How much time clapses before the motorcycle is even with the car? b) How far will each have traveled during that time? ¢) What is the relative velocity of the car with respect to the motorcycle when the two are even with each other? . These ProbMrag ave Coamplx =>Whnk A qwvenS + Drvem SFa¥rmendt Lfor ma—hismeans PeShe Kmoms & Car NNOTOVOAM, oA twfo 10 S =25 Sovwa= O ) 3 oc \/OM-:— @) d“aOrM e a eq- apy _ SVt ok o) Want 2 Unao e Se= Swe Cahhs;c;\w—;q ML A ISR CRA LA - > fv\u 9 volues wn Sor c%,,%i“;v\’o\ﬂ CALR o gc.:goc*%g-%qc‘{l > 2 225 (33 omit) () Se;_&:'“\:,f A€ vuant Se= Som* VoS ot '3 5, O~ 5 (WmIs) kT R 1 wwn Sm=Sc \37 \/\)ERM Ars¥once ei(/\/\ N avel )'P\Ug e (wo?@m (a —) ._-—_) kv *.A - "\’a{ )\/OIM——\/C/G——\/YV\/G need Ve VMan ?,-» usMD v = Ve = L el SRR g A L. Gop ! e 20