(Solved by Humans)-a) For the truss shown above the counters are flexible rods which

Question

a)??? For the truss shown above the counters are flexible rods which carry tension only.
ENGINEERING MECHANICS
AUTUMN 2016
ASSIGNMENT 2
This assignment is due before 5pm on Friday 6 th May, 2016.
Note: All of these questions have been taken from past exam papers. Where
marks are indicated they are the marks allocated for that question in the exam it
was taken from ? this is to give you an idea of the standard you need to work to in
the final exam.
QUESTION 1 (20 marks)

a) For the truss shown above the counters are flexible rods which carry tension
only.
i). Use the method of sections through IJ, IN, ND and DC to calculate the
force in member IJ.
ii). Knowing IJ, take another section through the truss to determine whether FI
or DG is the counter that is acting in tension. Explain why you think this
counter is the one acting in tension.
iii).
Determine the magnitude of the tension force acting in the counter you
selected in part (ii).

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b) In the diagram of the truss shown above the reaction at the roller at I is
4.25 kN upwards. Using the method of joints, calculate the force in
member FH.
c) Assuming you know what the reactions are at A and I, if you start at joint A,
can you solve for the force in all members of the truss by only using the
method of joints? Why, or why not?
QUESTION 2 (20 marks)

10 kN

a) The truss shown above carries the two loads at B and C as indicated.
i).
ii).
iii).

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Use the method of joints starting at joint C to determine the force in every
member of the truss. Indicate these forces on a line diagram of the truss.
Determine the reactions at the pin supports at A and D.
A further 1 kN load is applied on EC as indicated by the broken line in the
diagram. Discuss, without any calculations, why this would normally be

considered bad practice for this type of structure and what the probable
result would be.
b) For the three pin arch shown below determine the reactions at A and C.

QUESTION 3 (8 marks)

Each member of the truss shown above can safely support a tensile force of 50 kN
and a compressive force of 40 kN. Based on these limits, what is the largest
downward load F that can safely be applied at C?
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QUESTION 4 (20 marks)
a) Using one section only, use the
method of sections to calculate the
force in truss member FI in the truss
shown to the left.
b) Using the method of sections and/or
the method of joints calculate the
force in members EG and GJ in this
truss.

c) For the pin-jointed frame shown above, calculate the force in member
BE.
d) Why is this structure referred to as a frame and not a truss?
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QUESTION 5 (12 marks)

a) For the truss shown above:
a. Identify the zero force members and indicate these on the diagram
above. Justify your selection.
b. Determine the force in all members of the truss using any combination
of methods that you choose.

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