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PROBLEM 16.118
The 10-lb-uniform rod AB has a total length 2L = 2 ft and is
attached to collars of negligible mass that slide without friction
along fixed rods. If rod AB is released from rest when
30 ,
θ
= °
determine immediately after release (a) the angular acceleration of
the rod, (b) the reaction at A.
PROBLEM 16.119
A 40-lb ladder rests against a wall when the bottom begins to slide out. The
ladder is 30 ft long and the coefficient of kinetic friction between the ladder
and all surfaces is 0.2. For θ = 40°, determine (a) the angular acceleration of
the ladder, (b) the forces at A and B.
PROBLEM 16.119 (Continued)
Solving the i components of (5): (6)
Substitute into (6)→(5): (7)
Solve (9) for NA): (10)
(a) Substitute in known values:
(b)
2
A
ad
a
=
dc
aa
= +a ij
A k kA
( )
2
1
k
Ak
mc g d
N
a µa
µ
++
=+
( )
k
cg d
a µa
++
( ) ( ) ( ) ( )
22
+
11
kk
k kk
kk
mcg d cg d
d c c dm d I
a µa a µa
µ µ µ aa
µµ
++ ++
− + −=
++
( ) ( )
( ) ( ) ( ) ( )
22
22
+
11
k kk
kk
kk
k kk
kk
mg mg
dc cd
mcd cd
I d c c dm d
µ µµ
aµµ
µ µµ
µµ
−+
=
++
− − −+ −
++
2
-0.510 rad/s
a
=
B
2.70 lb.
kB
N
µ
=
31.80 lb
A
F=
78.7°
PROBLEM 16.120
A beam AB of length L and mass m is supported by two cables as shown. If
cable BD breaks, determine at that instant the tension in the remaining cable as
a function of its initial angular orientation
θ
.
PROBLEM 16.121
End A of the 6-kg uniform rod AB rests on the inclined surface, while end B is
attached to a collar of negligible mass which can slide along the vertical rod
shown. Knowing that the rod is released from rest when
θ
= 35° and neglecting the
effect of friction, determine immediately after release (a) the angular acceleration
of the rod, (b) the reaction at B.
PROBLEM 16.121 (Continued)
()
1.4333 m 0.75 m cos55 1.0031 mED EB DB
= − = − °=
0.75 sin55 0.61436 mDG = °=
( )
59.04 1.125 2.2646 6.3778
a
=++
2
yx
( ) ( ) ( )
6 9.81 0.75 cos55 1.5 sin55B°− °
2
16 1.5 6.263 6 6.282 0.75 cos55 6 3.848 0.75 sin55
PROBLEM 16.122
End A of the 6-kg uniform rod AB rests on the inclined surface, while end B is
attached to a collar of negligible mass which can slide along the vertical rod
shown. When the rod is at rest a vertical force P is applied at B, causing end B of
the rod to start moving upward with an acceleration of 4 m/s2. Knowing that
θ
= 35°, determine the force P.
PROBLEM 16.122 (Continued)
1.4333 0.75 cos55 1.0031 mED EB DB
= − = − °=
0.75 sin55 0.61436 m
DG = °=
PROBLEM 16.123
End A of the 8-kg uniform rod AB is attached to a collar that can
slide without friction on a vertical rod. End B of the rod is
attached to a vertical cable BC. If the rod is released from rest in
the position shown, determine immediately after release (a) the
angular acceleration of the rod, (b) the reaction at A.
PROBLEM 16.123 (Continued)
eff
( ) : sin
2
xx x
L
F F A ma m
aθ
Σ=Σ = =
3cos sin
Lg
