# Mechanics Assignment ```The geometry of a structure before the force P is applied is shown, where member ABC is horizontal and spring
AD is unstretched. The pulley at C is frictionless. Assume d is small enough so that the geometry of the displaced
structure is essentially the same as the geometry before loads are applied. Take the value of P to be 440 N.
References
Section Break
1.
Difficulty: Medium
Award: 10.00 points
Determine the vertical displacement d of point A, the forces supported by cable BCD and the spring, and the
reaction between the roller A and the wall to the right of it due to the 440 N force.
The vertical displacement of point A is
The force supported by cable BCD is
The force supported by the spring is
mm ↓.
N ↗.
N ↑.
The reaction between the roller A and the wall to the right of it is
N ←.
References
Numeric
Response
Difficulty: Medium
Structure ABCDE is supported by a frictionless collar at B and by cable AG. Bar FG has circular cross section and
is built in at F. Portion DE of the structure is parallel to the x axis. Take the value of P to be 500 N.
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Section Break
2.
Difficulty: Medium
Award: 10.00 points
The structure ABCDE is statically determinate and it is partially fixed.

True

False
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True / False
3.
Difficulty: Easy
Award: 10.00 points
Determine the force supported by the cable and all of the reactions at B.
The force supported by the cable is
N ↗.
The x component of the reaction force at B is
N ←.
The y component of the reaction force at B is
N ↑.
The reaction moment at B about the x axis is
N&middot;mm ↺.
The reaction moment at B about the y axis is
N&middot;mm ↺.
References
Numeric
Response
Difficulty: Medium
A model for the control arm ABCD for the suspension of one of the wheels of an automobile is shown. The
control arm is supported by ball-and-socket joints at points A and C, and by a spring BE. Points A, C, and E lie in
the yz plane and are attached to the frame of the automobile. The vertical force P = 4.4 kN is due to the weight of
the automobile, and the control arm has negligible weight.
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Section Break
4.
Difficulty: Medium
Award: 10.00 points
The control arm is statically determinate.

True

False
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True / False
5.
Award: 10.00 points
Difficulty: Easy
Determine the force in spring BE.
The spring force is
kN compression.
References
Numeric
Response
Difficulty: Hard
A foldable tray for the paper supply of a photocopy machine is shown. The tray is supported by a single hinge at
A and two slotted links (one on each side of the tray). The stack of paper weighs W = 19 N and other weights may
be neglected.
References
Section Break
6.
Difficulty: Medium
Award: 10.00 points
Determine the reactions at the hinge and at point B for one of the links.
The horizontal component of the reaction at the hinge is
N →.
The vertical component of the reaction at the hinge is
The reaction at point B for one of the links is
References
Numeric
Response
Difficulty: Medium
N ↓.
N ↖.
The horizontal bar ABCD is supported by a link BE with the shape shown. All pins are frictionless, and slots (if
present) are loose-fitting. Take the value of P to be 74 N.
References
Section Break
7.
Difficulty: Medium
Award: 10.00 points
Determine the reactions that support bar ABCD.
The reaction force at B (FBE) is
N ↙.
The vertical component of the reaction force at A is
N ↑.
The vertical component of the reaction force at C is
N ↑.
References
Numeric
Response
Difficulty: Medium
−
→
ˆ
A circular plate with weight W = −220 k
lb acting at its center, point F, is supported by cord DE and a thrust
bearing at B. Shaft AC is fixed and frictionless.
References
Section Break
8.
Difficulty: Medium
Award: 10.00 points
Determine the cable tension for the circular plate.
The cable tension for the circular plate is
lb ↖ .
References
Numeric
Response
Difficulty: Medium
The I beam shown is statically indeterminate. Under certain circumstances, it may be appropriate to use a model
where the I beam is rigid and the roller supports at points B and C are replaced by vertical springs of equal
stiffness so that the support reactions may be determined. Take the value of P to be 900 lb.
References
Section Break
9.
Difficulty: Medium
Award: 10.00 points
Determine the reactions at points A, B, and C using this approach.
The horizontal component of the reaction force at A is
lb →.
The vertical component of the reaction force at A is
lb ↑.
The vertical component of the reaction force at B is
lb ↑.
The vertical component of the reaction force at C is
lb ↑.
References
Numeric
Response
Difficulty: Medium
The brake pedal ABCD for an automobile has a torsional spring at pin C. The spring has 4000 N&middot;mm/rad stiffness
and is prewound by 1/2 of a turn so that contact is made at point E when P = Q = 0. The pedal has negligible
weight. Take the value of P to be 95 N.
References
Section Break
10.
Difficulty: Medium
Award: 10.00 points
Determine the value of Q that will cause the pedal to begin to move and the reactions at C.
The value of Q that will cause the pedal to begin to move is
The horizontal component of the reaction force at C is
The vertical component of the reaction force at C is
References
Numeric
Response
Difficulty: Medium
N ↘.
N ←.
N ↑.
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