Statics 2e 725
Problem 5.90
Identify each of the members cited below as a zero-force, two-force, three-force, or multiforce member.
Drum and contents in Example 5.5 on p. 287.
Solution
Problem 5.91
Identify each of the members cited below as a zero-force, two-force, three-force, or multiforce member.
Drum and contents in Example 5.6 on p. 288.
Problem 5.92
Identify each of the members cited below as a zero-force, two-force, three-force, or multiforce member.
Member ABC in Prob. 5.3 on p. 289.
Problem 5.93
Identify each of the members cited below as a zero-force, two-force, three-force, or multiforce member.
Step AB in Prob. 5.4 on p. 289.
Solution
Problem 5.94
Identify each of the members cited below as a zero-force, two-force, three-force, or multiforce member.
Members ABCD and DE in Prob. 5.5 on p. 289.
Solution
Problem 5.95
Identify each of the members cited below as a zero-force, two-force, three-force, or multiforce member.
Tray AB and link BC in Prob. 5.8 on p. 290.
Problem 5.96
Identify each of the members cited below as a zero-force, two-force, three-force, or multiforce member.
Member ABC in Prob. 5.22 on p. 292.
Problem 5.97
Identify each of the members cited below as a zero-force, two-force, three-force, or multiforce member.
Member ABCDE in Prob. 5.25 on p. 293.
Problem 5.98
Identify each of the members cited below as a zero-force, two-force, three-force, or multiforce member.
Wrench ABC in Prob. 5.37 on p. 295.
Problem 5.99
A handheld mixer for blending cooking ingredients is shown. To minimize
operator fatigue, the reaction forces on the operator’s hand should be as small as
possible. With this goal in mind, should the beaters rotate in the same direction
or opposite directions? Assume each beater produces a moment about the
´
axis, and if needed, assume reasonable values for dimensions. Explain your
reasoning.
Problem 5.100
When you evaluate the solution of a problem, you should always verify the accuracy of the solution, and
when possible, performing simple checks can help with verification. In Example 5.16 on p. 336, consider
the specific position
D0
, analyze the problem afresh to determine the hydraulic cylinder force required
to begin opening the dump, and verify that the results of Example 5.16 are in agreement. As another check,
Fig. 3 in Example 5.16 shows that the hydraulic cylinder force is zero for a particular tilt angle. Explain
why this occurs and, if possible, perform a simple analysis that confirms the value of
at which this force
is zero.
Solution
Solving Eq. (5) for the force FAB required to begin opening the dump results in
FAB D318 kN:(6)
Problem 5.101
A machine for sanding wood floors is shown. The machine weighs
80 lb
with
center of gravity along the
´
axis. At each sanding drum a moment of
60 in.lb
is applied to the machine in the direction opposite the rotation of the drum; in
addition to this moment, each drum has a
´
-direction reaction force, and all
other reactions are zero. Assume the operator’s hands, positioned at points
C
and
D
, can apply forces in the positive or negative
x
direction. Determine the
forces on the operator’s hands if
(a) Both sanding drums rotate about the positive ´direction.
(b)
The sanding drums at
A
and
B
rotate about the positive and negative
´
directions, respectively.
Problem 5.102
Bar
EF
has a square cross section and is fixed in space. The structure
ABC
has negligible weight and has a collar at
C
that has a square hole that slides
freely on bar
EF
. The structure
ABC
supports a uniform rectangular sign
with weight
1kN
(the two vertical edges of the sign align with points
A
and
B
). Determine the magnitude of the tension in cable
AD
and all of the reaction
components at Creferred to the x,y, and ´directions provided.
Problem 5.103
Structure
ABCDE
is supported by a frictionless collar at
B
and by cable
AG
.
Bar
F G
has circular cross section and is built-in at
F
. Portion
DE
of the
structure is parallel to the xaxis.
(a)
Is structure
ABCDE
statically determinate or statically indeterminate,
and is it fully fixed or partially fixed? Explain.
(b)
Determine the force supported by the cable and all of the reactions at
B
.
(4)
(5)
740 Solutions Manual
Problem 5.104
Structure
ABCDEF
is supported by a pin at point
A
, and point
F
rests on a
frictionless horizontal surface. Points
A
and
F
lie in the
xy
plane, and portion
BCDE
of the structure has the same
8in: ´
coordinate. The
10 lb
and
20 lb
forces act in the
´
direction. Determine all of the reactions at points
A
and
F
.
Problem 5.105
Bar
ABCDE
is supported by cable
BF
, a ball and socket at
A
, and a self-
aligning bearing at
E
. Determine the tension in cable
BF
and the reactions at
points Aand E.
Solution
)AyD0 ; (9)
Problem 5.106
Vertical bar
ED
has circular cross section and is built in at
E
. Member
ABC
is a single member that lies in a horizontal plane, with portion
BC
parallel to
the
´
axis and with cable
CD
attached to point
C
. The collar at
A
can freely
slide in the ydirection and can freely rotate about the yaxis.
(a)
Does the structure
ABC
have complete fixity or partial fixity, and is it
statically determinate or statically indeterminate? Explain.
(b)
When point
B
is subjected to a downward vertical force of
18 lb
, de-
termine the force supported by the cable and all support reactions at
A.
9.3in:/D0; (6)
XMA´ D0WMA´ CT6
9.6in:/18 lb .6in:/D0: (7)
Problem 5.107
Follow the suggestion made in Eqs. (10) and (11) of Example 5.13 on p. 331 to find the tension in cable
AC by summing moments about line OD.
Problem 5.108
In Prob. 5.107, find the tension in cable AD by summing moments about line OC .