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Unformatted text preview: Name Eel trim?“ ME 270  Fall 2008
Examination No. 1 INSTRUCTIONS Begin each problem in the space provided on the examination sheets. If
additional space is required, use the yellow paper provided to you. Work on one side of each sheet only, with only one problem on a sheet. Each problem is worth 20 points. Please remember that for you to obtain maximum credit for a problem, it
must be clearly presented, i.e. . the coordinate system must be clearly identified. . where appropriate, free body diagrams must be drawn. These should be
drawn separately from the given figures. 0 units must be clearly stated as part of the answer.
. you must carefully delineate vector and scalar quantities. If the solution: does not follow a logical thought process, it will be assumed in
error. When handing in the test, please make sure that all sheets are in the
correct sequential order and make sure that your name is at the top of
every page that you wish to have graded. Please circle your instructor’s name and section: Nauman Nauman Cook Murphy
9:3010:20 11:3012:20 2:303:20 9:0010:15
Problem 1
Problem 2
Problem 3 Total 9 Name SoldrcR/x I ma» ,» , ‘ "i*ﬁ‘;t‘l*l““>‘$\1ifll°6‘ ‘ ' 1. Below you will find a figure of a truss attached to the wall by a pin joint at B and a
cable that extends from G to A. Make sure you include all the appropriate free body
diagrams. _ 2.?
' L7}:
<—4m—><—4m—><—4m—*I 23
9: +0“. 35> 1a. Solve for the forces in the cable AG (6 points). 9 o 1c. Which of the links that you solved for in part (1b) are in tension (T) and which are in
compression (C)? Please circle the correct answer for each (3 points). GF ®3r C
GD @ or C 2. The tree below has been secured by cables stretching from A to points B, C, and D,
respectively. The base of the tree is located at (0, O, 0) m.
Z B (0,—1‘5, 0) m, (1.5, 0, 0.25)" m
)6 2a. If the force in cable AD is 1,560 N, write out the force in vector form (4 points). Y‘ ; “DugmLEt “A; _. (ml 4» a ’ ~ 0.233: +0:é(97§ 420(97):. ARI); [Igl/W Name So I ﬁrm, " ‘3' 5» ts: WamwwwaMs» ~ 2b. Determine the component of the force in the direction of cab! 6 points). Flvs‘lr / (:le TZ‘Q Wat Weior @ _4g
:93: (o’L\ «mus _)ME ”943 7 (igbgrvx ‘— 5’ng : 0L: “ 0,331‘ '— alsgylé V L » m Component: Em) 20. What moment does the force in AD exert about the base of the tree (5 points)?  r
[1— ”DAXEAD  m} x<~§1asﬂp 4— “WC/"A; — /0“0NE\ ‘ ’;L§IC\SN‘M\ ’3 (qu0 NM” 2d. What is the angle between cables AD artﬁ points)? AB
Co$9 : e 9, AM); “Ac P , 4g 6%,”; :, (03’, (€45 ' ’433 Name a mﬁ’iﬂwwa‘ '7 , A» » 3. The semicircular plate has a radius of 40 cm. The plate weighs 100 N with the center
of gravity at ((1, 0,0). k H??? Ball and socket TOO/m we; 22> e *6’“ ‘7’0 cm x no: mm A 14 saw \ 1/)
$170M J, 7;“) (094) (.(0969_ ' 0_ 3a. First, draw a free body diagram of the semi—circular plate, assuming the connection at
C is a ball—and—socket joint (6 points). Name 59 l mm WM» A s > ; w as «We ,, ,, 3b. Write out the equations of equilibrium and determine the tensile forces in cables AD
and DB. Please write your answers in vector form (8 points). if "i Q i’i/c :2 IAD: Ttbéﬁb
/~—~/ : am 0; ”Abs/w
‘ _ T ( 84
A: X (441$ K1): oSqf cos \
.. 1—5/3 1 ' 785 (0&5 s/r‘élé 4 7155 S/néf
+ Ewing x252 * 7L T71> (09:14 «56“ \ "yaw 4— wwg y (—mcogs sac; wgbmt W»; 7S +LIOLM§ X (739(08éﬂ0s9 — TAbéc9¢(os§\‘f~ :Q E: aJw +7 #Ocm ((177453:qu 6/2169
bx.) 30. Calculate the reactions at the ball and socket joint (6 points). {.520 1:1 6X  QTAD 4°ng éan =0 :5 Cx 1‘ 37% (0945 37149 :1: CUB~100N ‘l Qkaér/Mt) 3 0 Reactions: C, : ”1.1413 CV) ‘— HZJ“ N (2" an) ...
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 Fall '08
 MURPHY

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