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Unformatted text preview: Your
Recitation
TA:
_____________________________
Section
Number:
_____________________

 
 Your
NetID:
__________________
Your
Name:
________________________________________________
 ENGRD
2020
 Quiz
#
2
 Wed,
Oct
21,
2009
 
 Consider
the
structure
shown
below
in
static
equilibrium.
All
members
are
 massless.
Rigid
member
AB
is
vertical
and
has
cross‐seciton
area
=
1cm2.
The
 coefficient
of
static
friction
between
the
ground
and
rigid
member
BCD
is
µ.
Joints
A
 and
B
are
pin‐joints.
Load
P
is
applied
to
member
AB
with
its
line
of
action
along
BC.
 (Recall
that
sin(60°)
=
cos(30°)
=
√3/2
and
sin(30°)
=
cos(60°)
=
1/2).
 
 
 
 B
 
 P
=
2N
 
 
 
 
 
 
 
 
 θ
=
30°
 C
 
 D
 A
 
 µ
=
tan(30°)
=
1/√3
 
 
 (a) (6
points)
Find
friction
force
on
member
BCD.
 (b) (6
points)
The
normal
force
exerted
by
member
BCD
on
the
ground
is
 distributed
over
the
contact
area.
Is
the
resultant
of
this
distributed
normal
 load
on
the
left
of
C
or
on
the
right
of
C?
Find
its
minimum
magnitude.
 (Note
that
the
normal
force
is
statically
indeterminate,
but
you
can
find
its
 minimum
magnitude).
 (c) (6
points)
Is
the
member
AB
in
tension
or
compression?
 (d) 
(6
points)
Assuming
uniform
stress
distribution,
find
the
minimal
normal
 stress
developed
in
a
cross‐section
of
member
AB.
 
 
 Your
Recitation
TA:
_____________________________
Section
Number:
_____________________

 
 Your
NetID:
__________________
Your
Name:
________________________________________________
 ENGRD
2020
 Quiz
#
2
 Wed,
Oct
21,
2009
 
 
 ...
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This note was uploaded on 10/24/2009 for the course ENGRD 2020 taught by Professor Zehnder during the Fall '06 term at Cornell University (Engineering School).

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