Unlock document.
This document is partially blurred.
Unlock all pages and 1 million more documents.
Get Access
614 Solutions Manual
Part (c)
As indicated in Part (b), there are many ways to determine the moment of this couple. In general,
it is best to use ErDE or ErED so that only one cross product needs to be evaluated.
Problem 4.120
Frictionless pulleys at
B
and
C
are attached to member
BCEG
, which is
horizontal when
˛D0ı
. Wire
ABCD
wraps around the pulleys. End
A
of the
wire supports a weight
WD200
N, and end
D
of the wire is supported by a
frictionless pulley so that segment CD of the wire is always vertical.
Determine the moment that wire
ABCD
applies to member
BCEG
if
˛D20ı.
Solution
Problem 4.121
Frictionless pulleys at
B
and
C
are attached to member
BCEG
, which is
horizontal when
˛D0ı
. Wire
ABCD
wraps around the pulleys. End
A
of the
wire supports a weight
WD200
N, and end
D
of the wire is supported by a
frictionless pulley so that segment CD of the wire is always vertical.
(a)
Determine the moment that wire
ABCD
applies to member
BCEG
if
0ı˛90ı. Plot this moment versus ˛.
(b)
If
˛
may exceed 90
ı
, determine the largest value of
˛
, namely
˛max
, for
which your answer to Part (a) is valid.
Statics 2e 617
Problem 4.122
Determine values for P,Q,R,S, and MDso that the two force systems shown are equivalent.
Problem 4.123
A beam is subjected to the three forces shown.
(a)
Determine an equivalent force system at the midspan of the beam
xD
3m.
(b)
Determine an equivalent force system consisting of a single force, and
specify the
x
coordinate of the point where its line of action intersects
the xaxis.
Problem 4.124
A speed control mechanism for a small gasoline engine is shown.
(a) Determine an equivalent force system at point O.
(b)
Determine an equivalent force system consisting of a single force, and
specify the
y
coordinate of the point where its line of action intersects
the yaxis.
Solution
Problem 4.125
Aweldment is a structure or component built by welding an assembly of pieces
together. The weldment shown is subjected to three cable forces. Determine an
equivalent force system consisting of a single force, and specify the
x
coordinate
of the point where its line of action intersects the xaxis.
Solution
Problem 4.126
The wing of a jet supports a
900 lb
force due to the weight of an engine and
300 lb and 600 lb forces due to the weight of fuel.
(a) Determine an equivalent force system at point A.
(b)
Determine an equivalent force system consisting of a single force, and
specify the
x
and
´
coordinates of the point where its line of action
intersects the x´ plane.
Problem 4.127
A thin rectangular flat plate is loaded by the forces shown.
(a) Determine an equivalent force system at point O.
(b)
Determine a wrench equivalent force system, and specify the
y
and
´
coordinates of the point where the wrench’s line of action intersects the
y´ plane.
Solution
624 Solutions Manual
equations
O{components: 300 N
;(11)
Problem 4.128
A seat of a roller coaster is subjected to the forces shown during a turn. The
force at
A
is vertical, the forces at
B
and
C
are parallel to the
x
and
´
directions,
respectively, and the forces at
D
and
E
lie in planes parallel to the
y´
plane.
Determine an equivalent force system at point
O
, where the seat is attached to
the car.
Problem 4.129
For the roller coaster seat described in Prob. 4.128, determine a wrench equiva-
lent force system and specify the
x
and
´
coordinates of the point where the
wrench’s line of action intersects the x´ plane.
628 Solutions Manual
