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PROBLEM 8.39
Two rods are connected by a collar at B. A couple
M
A
with a
magnitude of 15 N·m is applied to rod AB. Knowing that the
coefficient of static friction between the collar and the rod is
0.30, determine the largest couple
M
C
for which equilibrium
will be maintained.
PROBLEM 8.40
In Prob. 8.39, determine the smallest couple
M
C
for
which equilibrium will be maintained.
PROBLEM 8.39
Two rods are connected by a collar at
B
. A couple
M
A
with a magnitude of 15 N·m is applied to rod
AB
.
Knowing that the coefficient of static friction between the
collar and the rod is 0.30, determine the largest couple
M
C
for which equilibrium will be maintained.
PROBLEM 8.40 (Continued)
PROBLEM 8.41
A 10-ft beam, weighing 1200 lb, is to be moved to the left onto
the platform. A horizontal force
P
is applied to the dolly, which
is mounted on frictionless wheels. The coefficients of friction
between all surfaces are
0.30
s
and
0.25,
k
and initially
2 ft.x
Knowing that the top surface of the dolly is slightly
higher than the platform, determine the force
P
required to start
moving the beam. (
Hint:
The beam is supported at
A
and
D
.)
PROBLEM 8.42
(
a
) Show that the beam of Problem 8.41
cannot
be moved if the
top surface of the dolly is slightly
lower
than the platform.
(
b
) Show that the beam
can
be moved if two 175-lb workers
stand on the beam at
B
and determine how far to the left the beam
can be moved.
PROBLEM 8.41
A 10-ft beam, weighing 1200 lb, is to be
moved to the left onto the platform. A horizontal force
P
is
applied to the dolly, which is mounted on frictionless wheels.
The coefficients of friction between all surfaces are
0.30
s
and
0.25,
k
and initially
2 ft.x
Knowing that the top
surface of the dolly is slightly higher than the platform,
determine the force
P
required to start moving the beam. (
Hint:
The beam is supported at
A
and
D
.)
PROBLEM 8.42 (Continued)
PROBLEM 8.43
Two 8-kg blocks
A
and
B
resting on shelves are connected by a rod of
negligible mass. Knowing that the magnitude of a horizontal force
P
applied at
C
is slowly increased from zero, determine the value of
P
for
which motion occurs, and what that motion is, when the coefficient of
static friction between all surfaces is (
a
)
0.40,
s
(
b
)
0.50.
s
PROBLEM 8.43 (Continued)
PROBLEM 8.44
A slender steel rod of length 225 mm is placed inside a pipe as
shown. Knowing that the coefficient of static friction between the rod
and the pipe is 0.20, determine the largest value of
for which the
rod will not fall into the pipe.
PROBLEM 8.45
In Problem 8.44, determine the smallest value of
for which the rod
will not fall out the pipe.
PROBLEM 8.44 A slender steel rod of length 225 mm is placed
inside a pipe as shown. Knowing that the coefficient of static friction
between the rod and the pipe is 0.20, determine the largest value of
for which the rod will not fall into the pipe.
