Truss: zero force members

Error

There was an error loading the page.

Contributors

William Haynes

Feedback

From users who are members of Engineering Statics :

William Haynes

said

Ready to use

4 years, 4 months ago

History

○

William Haynes 4 years, 4 months ago

Gave some feedback: Ready to use

○

William Haynes 4 years, 4 months ago

Gave some feedback: Needs to be tested

○

William Haynes 4 years, 4 months ago

Saved a checkpoint:

checkpoint before working on marking error. Currently that is broken.

Restore this checkpoint

○

William Haynes 4 years, 6 months ago

Gave some feedback: Has some problems

○

William Haynes 4 years, 7 months ago

Gave some feedback: Needs to be tested

○

William Haynes 4 years, 7 months ago

Saved a checkpoint:

stopped working with geogebra update

Restore this checkpoint

○

William Haynes 4 years, 7 months ago

Gave some feedback: Doesn't work

○

William Haynes 5 years, 3 months ago

Published this.

○

William Haynes 5 years, 3 months ago

Gave some feedback: Ready to use

○

William Haynes 5 years, 4 months ago

Created this.

There is only one version of this question that you have access to.

There are 3 other versions that do you not have access to.

Question statement

{applet()}

Scripts in part seems to cause breakage of marking algorithm - moved it to advise section.

Loads: down is positive

{f}

Loads and reactions: down is positive

{loads[0]} = {f[loads[0]]} {loads[1]} = {f[loads[1]]} {supports[0]} = {reactions[0]} {supports[1]} = {reactions[1]} $\Sigma M_A:$ = {13 x[loads[0]]+ 17 x[loads[1]] + reactions[0] * x[supports[0]] + reactions[1] * x[supports[1]]}

Forces in members: Tension is positive

{m}

Joint Equilibrium:

Joint A: {polar(f["A"], -90) + polar(AB,0) + polar(AG,30)}

Joint B: {polar(f["B"], -90) + polar(AB,180) + polar(BC,0) + polar(BG,120) + polar(BH,60) }

Joint C: {polar(f["C"], -90) + polar(BC,180) + polar(CD,0) + polar(CH,120) + polar(CN,60) }

Joint D: {polar(f["D"], -90) + polar(CD,180) + polar(DE,0) + polar(DO,120) + polar(DL,60)}

Joint E: {polar(f["E"], -90) + polar(DE,180) + polar(EF,0) + polar(EL,120) + polar(EM,60)}

Joint F: {polar(f["F"], -90) + polar(EF,180) + polar(FM,150)}

Joint G: {polar(f["G"], -90) + polar(GH,30) + polar(AG,-150) + polar(BG,-60)}

Joint H: {polar(f["H"], -90) + polar(HN,0) + polar(CH, -60) + polar(BH,-120) + polar(GH, -150) + polar(HI, 30)}

Joint I: {polar(f["I"], -90) + polar(IJ,30) + polar(NI,-60) + polar(HI,-150)}

Joint J: {polar(f["J"], -90) + polar(JK,-30) + polar(JO,-60) + polar(JN,-120) + polar(IJ,-150)}

Joint K: {polar(f["K"], -90) + polar(KL,-30) + polar(KO,-120) + polar(JK,150)}

Joint L: {polar(f["L"], -90) + polar(LM,-30 ) + polar(EL, -60) + polar(DL,-120) + polar(LO, 180) + polar(KL, 150)}

Joint M: {polar(f["M"], -90) + polar(FM,-30) + polar(EM,-120) + polar(LM,150)}

Joint N: {polar(f["N"], -90) + polar(NI,120 ) + polar(HN, 180) + polar(JN,60) + polar(CN,-120)}

Joint O: {polar(f["O"], -90) + polar(KO, 60) + polar(LO, 0) + polar(JO,120) + polar(DO, -60)}

Give any introductory information the student needs.

			Name	Type	Generated Value

points	list	List of 15 items
members	list	List of 27 items
loads	list	[ "J", "D" ]
supports	list	[ "C", "B" ]
f	dict	Dictionary with 15 entries
m	dict	Dictionary with 27 entries
x	dict	Dictionary with 15 entries
reactions	list	[ -77, 47 ]
zeroForce	list	List of 27 items
num_ans	number	10

			Name	Type	Generated Value

AB	number	0
AG	number	0
BC	number	-27.1354626519
BG	number	0
BH	decimal	dec("5.427092530382479972771997073437703059745e+1")
CD	decimal	dec("-9.814954576223639659977725203733502038821")
CH	decimal	dec("-2.713546265191240739438663740104234625162e+1")
CN	decimal	dec("-6.177647880328992407443118699357534217398e+1")
DE	number	0
DL	decimal	dec("-1.659977725203733502038821e-15")
DO	decimal	dec("1.962990915244727765997772520373350203882e+1")
EF	number	0
EL	number	0
EM	number	0
FM	number	0
GH	number	0
HI	decimal	dec("4.699999999999998244369050202402000000001e+1")
HN	decimal	dec("2.027228002926562296940255e-14")
IJ	decimal	dec("4.699999999999998244369050202402000000001e+1")
JK	number	-2.8751657594854747*10^(-15)
JO	decimal	dec("1.962990915244728065997772520373350203882e+1")
JN	decimal	dec("-6.177647880328988352987112846232940336888e+1")
KL	number	-2.8751657594854747*10^(-15)
KO	number	0
LO	number	3.319955450407467*10^(-15)
LM	number	0
NI	number	0

			Name	Type	Generated Value

answers

list

List of 27 items

Automatically regenerate variables?

Name

Data type

Value

xxxxxxxxxx
 
["A","B","C","D","E", "F","G","H","I","J", "K","L","M","N","O"]

JME function reference

Description

names of the points

Describe what this variable represents, and list any assumptions made about its value.

Can an exam override the value of this variable?

Generated value: `list`

[ "A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O" ]

This variable doesn't seem to be used anywhere.

Parts

Choose several from a list

Choose several from a list

Ask the student a question, and give any hints about how they should answer this part.

Select all {num_ans} zero-force members to receive full credit.

Minimum marks

Maximum marks

(no maximum)

Show correct answer on reveal?

Show score feedback icon?

Advanced settings

Number of display columns

Minimum answers

Maximum answers

What to do if wrong number of answers selected:

Custom marking matrix?

Custom matrix expression

Show choice feedback state?

Marking method

For each choice, specify the number of marks to add or subtract when the student picks it.

Variable list of choices?

List of choices

Shuffle order of choices?

Advice

Look for situations like 1a) and 2a) in the diagram below.

In figure 1a), members $AB$ and $AC$ share the same line of action and member $AD$ is zero-force. If a load is added to $A$, then member $AD$ must pick up load to support it and will not be zero-force.

If figure 2a), members $AB$ and $AC$ do not share the same line of action and both must be zero-force to maintain equilibrium of joint $A$. If a load is added at $A$ as shown in figure 2b) then $AB$ and $AC$ will pick up load to maintain equilibrium.

When a member is identified as zero-force, then it may produce zero-force members at adjacent joints.

Give a worked solution to the whole question.

URL

Text alternative

Use this tab to check that this question works as expected.

There was an error which means the tests can't run:

Part	Test	Passed?
Choose several from a list
Choose several from a list		Hasn't run yet

This question is used in the following exams:

Chapter 06 Exercises by Michael Proudman in Engineering Statics.
29. Special Loading Conditions by Michael Proudman in Engineering Statics.
29. Special Loading Conditions by William Haynes in Engineering Statics.
Chapter 6 Exercises by William Haynes in Engineering Statics.

Loading...

Error

Metadata

Taxonomy: mathcentre

Taxonomy: Kind of activity

Taxonomy: Context

Contributors

Feedback

History

Comment

Checkpoint description

William Haynes 4 years, 4 months ago

William Haynes 4 years, 4 months ago

William Haynes 4 years, 4 months ago

William Haynes 4 years, 6 months ago

William Haynes 4 years, 7 months ago

William Haynes 4 years, 7 months ago

William Haynes 4 years, 7 months ago

William Haynes 5 years, 3 months ago

William Haynes 5 years, 3 months ago

William Haynes 5 years, 4 months ago

Error in variable testing condition

Error

Warning

Generated value: `list`

Parts

Choose several from a list

Advanced settings

Loading...

Error

Truss: zero force members

Metadata

Taxonomy: mathcentre

Taxonomy: Kind of activity

Taxonomy: Context

Contributors

Feedback

History

Comment

Checkpoint description

William Haynes 4 years, 4 months ago

William Haynes 4 years, 4 months ago

William Haynes 4 years, 4 months ago

William Haynes 4 years, 6 months ago

William Haynes 4 years, 7 months ago

William Haynes 4 years, 7 months ago

William Haynes 4 years, 7 months ago

William Haynes 5 years, 3 months ago

William Haynes 5 years, 3 months ago

William Haynes 5 years, 4 months ago

Error in variable testing condition

Error

Warning

Generated value: list

Parts

Choose several from a list

Advanced settings

Generated value: `list`