Worksheet 3 - WordPress.com

Worksheet 3
On Chapter 4: Analysis of Simple Structures
Part I: Theoretical Questions
1. Differential between a plane truss and a simple truss.
2. In truss analysis, it is always possible to exclusively use either the method of joints or the
method of sections. However, sometimes combining both techniques may help an
engineer arrive at the magnitude of the force in a member more readily. Think of such a
situation and describe it here.
3. In analyzing a truss using the method of sections, the cut section should not pass through
more than 3 members. Why is this?
4. Match the following two columns
Column II
Column I
1. Internal determinacy
2. Internal indeterminacy
3. Collapse (Structure is
deficient of internal
members)
A. 2j < m + 3
B. 2j = m + 3
C. 2j > m + 3
Where j is number of joints and m
is number of members
5. Discuss similarities and differences between frames and machines
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Engineering Mechanics: Statics Assignment 4
Chapter 4
Part II: Numerical Analysis
Note: Here, vector quantities are represented in bold-face letters whereas their scalar
counterparts are represented by normal-face letters.
1. Determine the force in each member of the loaded truss using the method of joints. All
triangles are equilateral.
Answer:
2. The truss supports a ramp (shown with a dashed line) which extends from a fixed
approach level near joint F to a fixed exit level near J. The loads shown represent the
weight of the ramp. Determine the forces in members BH and CD using the method of
sections.
Answer: BH = 0.683L T,
CD = 1.932L C
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Engineering Mechanics: Statics Assignment 4
Chapter 4
3. Determine the forces in members AB, BI, and CI of the simple truss. (Hint: 1) All curved
members are two-force members; 2) Take advantage of the symmetry of the structure to
find relevant angles)
Answer: AB = 2.26L T, BI
= LT, CI = 0.458L T
4. The nose-wheel assembly of a certain airplane is raised by the application of a torque M
to link BC through the shaft at B. If the arm and wheel AO have a combined weight of
400 N with center of gravity at G, find the value of M necessary to lift the wheel when D
is directly under B, at which position angle θ is 30o. All measurements given are in
centimeters.
Answer: M = 5000 N-cm CCW
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