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Statics practice midterm with solutions
Typology: Summaries
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QuesƟon 1 (20 points)
For the cables shown in figure 1, it is known that
the maximum allowable tension is 600 N in cable
AC and 750 N in cable BC. Determine:
(a) The maximum force P that can be applied at
C ,
Use the Trigonometric solution method Figure 1
Question 2 (30 points)
Pulleys A and B are mounted on bracket CDEF as shown
in Figure 2. The tension on each side of the two belts is as
shown.
equivalent force, and
3. Determine where the single equivalent force line of
action intersects the bottom edge of the bracket
between points F and E. Figure 2
SOLUTION
Equivalent force-couple at A due to belts on pulley A
We have F : 120 lb 160 lb RA
R A 280 lb
We have M (^) A : 40 lb(2 in.) MA
M A 80 lb in.
Equivalent force-couple at B due to belts on pulley B
We have F : (210 lb 150 lb) 25 R B
R (^) B 360 lb 25°
We have M B : 60 lb(1.5 in.) MB
M B 90 lb in.
Equivalent force-couple at F
We have F : R (^) F ( 280 lb) j (360 lb)(cos 25 i sin 25 j )
2 2
2 2
1
1
(326.27 lb) (127.857 lb)
350.43 lb
tan
tan
F
Fx Fy
Fy
Fx
i j
or R (^) F R 350 lb 21.4° ◄
We have M F : MF (280 lb)(6 in.) 80 lb in.
[(360 lb) cos 25 ](1.0 in.)
[(360 lb) sin 25 ](12 in.) 90 lb in.
M (^) F (350.56 lb in.) k
To determine where a single resultant force will intersect line FE ,
350.56 lb in.
127 857 lb
2.7418 in.
F y
F
y
M dR
d R
or d 2.74 in.◄
