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Unformatted text preview: PROBLEM 2.9 Two control rods are attached at A to lever AB. Using trigonometry and ‘ F“ knowing that the force in the righthand rod is F2 = 20 lb, determine
“——f (a) the required force F l in the lefthand rod if the resultant R of the
forces exerted by the rods on the lever is to be vertical, (b) the corresponding magnitude of R. SOLUTION
Using the Law of Sines i _ R _ 201b sina sm38° sinﬁ 0‘ = 90°  10° = 80°,ﬁ = 180° — 80° — 38° = 62° Then: Fl _ R _ 201b sin80° sin38° sin62° . or (a) Fl = 22.3 lb 4
(b) ,R = 13.951b 4 PROBLEM 2.18 For the hook support of Prob. 2.7, determine, using trigonometry, the
magnitude and direction of the resultant of the two forces applied to the support knowing that P = 500 N and a = 60°. SOLUTION
Using the triangle rule and the Law of Cosines,
Have: 6 = 180° — 45°
6 = 135°
Then:
R2 = (900 N)2 + (500 N)2 — 2(900 N)(500 N) cos135° or R = 1302.46 N Using the Law of Sines, 500 kN _ 1302.46 N
siny sin135° or y = 15.7056°
and [3 = 60° + 15.7056° [a = 75.751° R = 1.302 kN 4: 758° { PROBLEM 2.23 Determine the x and y components of each of the forces shown. 7
250mm
t
110 mm
7
SOLUTION
A \
\ I. 3, Determine the following distances:
QSON I /
ago N dOA = ,/(—160 mm)2 + (300 mm)2 = 340 mm
0
(a '0 N dOB = (600 mm)2 + (250 mm)2 = 650 mm
\‘c. doc: (600mm)2+(—110mm)2 =610mm
680 N Force: P; = 680 NM
340 mm
P; = —320 N 4
300
Fy = 680 N( m)
lTllTl
Fy = 600 N 4
390 N Force: 5; = 390 NM
650 mm
P; = 360 N 4
F = 390 N (250 m)
y 0 mm
Fy = 150 N 4
610 N Force: P; = 610 NM
610 mm
P; = 600 N 4
—110
Fy = 610 N( m)
10 mm F.=—110N< PROBLEM 2.34 Determine the resultant of the three forces of Prob. 2.23. T Problem 2.23: Determine the x and y components of each of the forces mm shown 110 lnm _f SOLUTION From Problem 2.23: FDA = —(320 N)i + (600 N) j
FOB = (360 N)i + (150 N)j
FOG = (600 N)i — (110 N)j
R = 2F = (640 N)i + (640 N)j
R = (640 N)2 + (640 N)2
= 905.097 N 640N
640N tana= a = 45.0° R=905 N A: 45.0° { ...
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This note was uploaded on 10/05/2009 for the course CE statics taught by Professor Epstein during the Spring '09 term at UConn.
 Spring '09
 Epstein

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