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8/13/2019 Stress and Strain Hooke's Law
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Lesson: Stressed and StrainedContributed by: Integrated Teaching and Learning Program, College of Engineering, Universityof Colorado at Boulder
Engineering Connection
Engineering analysis or artial designEngineers use their understanding of forces, stress, strain and material roerties to create safe
designs for structures, e!uiment and roducts" #nalysis of strength of materials $yield strength,ultimate tensile strength and fatigue strength% figures into the selection of materials used to create
items such as chairs, aliances, toys, bicycles, medical &oint relacements, roc' climbing roe,
door handles, roof shingles, (ater slides, diving boards, bridges and layground e!uiment, to
name a fe("
Learning Objectives
#fter this lesson, students should be able to: )ecogni*e that engineers use their understanding of forces, stress, strain and material
roerties to create safe designs for structures, e!uiment and roducts
Understand ho( force and area affect stress"
+istinguish bet(een comression and tension"
Understand several roerties of materials
Introduction/Motivation
The handson Stress #naly*er Bench e-hibit at the ITL Laboratory at the
University of Colorado at Boulder demonstrates ho( different structures
handle different stress loads" These hotograhs sho( a lastic bridge structurevie(ed through a olari*ing filter that enables a erson to see, via color
changes, the areas e-eriencing stress" In the hotograh on the right, note the
resulting change in stress on the bridge due to the finger ushing do(n on thestructure"
Stress is a funny (ord because it can mean different things" Stress can be (hat causes your hairto turn gray because you have too much home(or' or deadlines to meet" That.s mental stress"
/hen engineers tal' about stress, they mean ho( much force an ob&ect e-eriences, and ho(
that force is sread over the ob&ect.s area" E-amles of engineering stress are ongoing everyday,
every(here around you, from chairs to cars to bridges to buildings"
Summary
Students are introduced to the concets of stress and strain (ith
e-amles that illustrate the characteristics and imortance of these
forces in our everyday lives" They e-lore the factors that affectstress, (hy engineers need to 'no( about it, and the (ays engineers
describe the strength of materials" In an associated literacy activity,
(hile learning about the stages of grou formation, grou dynamicsand team member roles, students discover ho( collective action can
alleviate ersonal feelings of stress and tension"
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# man named )obert 0oo'e described the concet of stress in 1223, and engineers have been
using it ever since" 4or e-amle, engineers analy*e ho( stress affects the chairs (e sit in so that
the legs are strong enough to not bend or brea'" Stress analysis is imortant to 'ee the (heelson your car and bridges standing u" 5aterials must be strong enough to (ithstand the stress
uon them" If materials are not strong enough, terrible accidents can haen, such as a floor
collasing because too many eole are standing on it6 Understanding stress and the strength ofmaterials is very imortant to 'ee us safe in our daytoday lives6
Stress andstrengthare imortant arameters for engineers to understand" Stress is a measure of
ho( much force an ob&ect e-eriences er unit area, andstrength is a material.s ability to(ithstand stress" /hen the stress e-ceeds the strength of a art, it fails" That is (hat haened in
the 0yatt )egency 0otel in 7ansas City in 1891, (hen too many eole (ere dancing on a
s'y(ay bridge in the hotel atrium and it collased, 'illing 11 eole" Engineers determine
(here the stress (ill be the highest on an ob&ect so that art can be redesigned or reinforced"Engineers also secify the materials that ob&ects and structures are made of, so that airlanes can
fly safely, (heels do not fall off of automobiles, chairs suort the (eight of eole, bridges
suort the loads that travel them, and so on"
Lesson Background & Concepts for Teachers
Stress
Stress is a measurement of force sread over area" ;ne (ay to thin' of stress is to imagine the
different results that haen (hen a erson stands on a tramoline and (hen a erson lays do(non a tramoline" # erson standing on a tramoline concentrates the force of his stress
F> 4orce ?@e(tons or lbsA
A> Crosssectional area ?mor inAThis e!uation mathematically tells us the same conclusion as our thought e-eriment (ith the
tramoline" 4or a constant force $F%, if the area $A% is a small number, the stress $=% $ronounced
sigma% (ill be larger" Similarly, if the area is larger, the stress (ill be smaller"
This mathematical definition is not limited to tramolines" Comuting stress (or's for all sortsof ob&ects e-eriencing all sorts of different forces" /e can comute the stress on ob&ects that are
either being comressed or ulled aart" 4or e-amle, if a roe brea's (hen a certain force is
alied, using a bigger diameter roe (ill reduce the stress because the crosssectional area islarger" #nd, if there is less stress on the roe, it might not brea'6
Compressive and Tensie Stresses
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Comression occurs (hen something is being s!uee*ed together" #s (ith the general discussion
of stress above, compressive stressis created by forces sread over an area" 4or e-amle, as you
sit in a chair, the legs of the chair are e-eriencing comressive stresses because they are beings!uee*ed bet(een you and the floor"
;n the other hand, tensile stressoccurs (hen something is being ulled aart" # roe in a tugo
(ar e-eriences tensile stress" )oes can only resist tensile stresses and not comressivestresses, because they are fle-ible" In other (ords, you cannot ush a roe"
Strain
Strainis a measurement of ho( an ob&ect reacts to stress" Strain is simly a measurement of (hat
the ercentage change in an ob&ect.s shae is (hen a certain stress is alied to it" # good (ay todemonstrate strain is (ith a rubber band" Suose (e have a rubber band that is 133 inches long"
@o(, (e add a tensile stress by hanging a certain amount of (eight from the rubber band, (hich
ma'es it 13D inches long" In this case, the rubber band e-erienced D strain because of the
stress created by the (eight" 5athematically, strain can be comuted by the e!uation:
/here F > strain $ercent%
L> ne( length $mm or in%
Lo> original length $mm or in%
!astic and "astic #eformation
/hen a material is strained, it is said to be deformed" ;nce a material has been deformed and the
stress is relieved, either one of t(o things (ill haen: The material goes bac' to its original
shae or the material stays deformed" If the material is able to go bac' to its original shae, it iscalled elastically deformed$for e-amle, a rubber band%" If the material is strained too much, it
(ill not be able to comletely return to its original shae and is calledplastically deformed$for
e-amle, silly utty%"Let.s use the e-amle of a layground seesa(" # seesa( bar tyically bends less than an inch
(ith t(o children on it, and returns to normal $no bend% (hen the 'ids get off" #n engineer
(ould say that, in this case, the seesa( bar (as elastically deformed" 0o(ever, if (e ut t(overy big adults on each side of the seesa( bar, it may bend it a fe( inches andstay bent$or even
brea'% (hen they leave" In this case, an engineer (ould say that the bar (as lastically deformed
$see illustration%"
The bro'en seesa( in this illustration (as lastically
deformed due to the large stress laced uon it" The seesa(
(ill not be able to return to its original shae"
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Proerties of 5aterials G The Big Three
Engineers use their understanding of forces, stress, strain and material roerties to create safe
designs" /e have already discussed forces, stress and strain, so that leaves material roerties")esearchers measure roerties of materials and ho( they behave under stress" $ied strength,
Sy, is the amount of stress a material can ta'e (ithout lastically $ermanently% deforming" If thestress is greater than the yield stress, the material (ill deform lastically, but not brea'" %timate
tensie strength $UTS%, Sut, is the amount of stress a material can ta'e before brea'ing" The UTSof a material is al(ays greater than or e!ual to the yield strength" The fatigue strength, Se, is the
stress a material can ta'e one million times over and over again, before brea'ing" Believe it or
not, that seesa( bar (ill become tired after 13 years of use and might give out one day if notdesigned roerly" The fatigue strength is al(ays less than or e!ual to the yield strength"
So ho( do engineers use this 'no(ledgeH If you (ere to design a safety roe for roc' climbers
you (ould (ant a roe that (ould e-erience stresses less than the Syand the Sut" This (ay, theroe stretches a little to hel absorb imact, but does not brea'" If you (ere to design layground
e!uiment, you (ould (ant to ma'e sure the stresses in the mon'ey bars (ere belo( Seso that
after a million uses they still (ill not brea'"
ocabuar'/#efinitions
Stress: The amount of force alied over the area of an ob&ect $comuted bydividing force by area%"
Compressive
stress:
Stress that s!uee*es a material together"
Tensile stress: Stress that ulls a material aart"
Strain: The ercent amount of elongation or comression of a material"
Elastic
deformation:
;ccurs (hen a material is strained $deformed%, but returns to its original
shae, li'e a rubber band"Plastic
deformation:
;ccurs (hen a material is strained $deformed% beyond its yield strength and
does not return to its original shae, li'e silly utty"
Yield strength: The ma-imum amount of stress a material can ta'e before it deforms
lastically $ermanently%"
Ultimate tensile
strength:
The ma-imum amount of tensile stress a material can ta'e before brea'ing"
Fatigue strength: The ma-imum amount of stress a material can ta'e one million times (ithout
brea'ing"
(ssociated (ctivities
Brea'ing Beams In this handson activity, student e-lore ho( different designs of
homemade clay beams handle stress and affect beam strength"
Team U6 /hile comleting a team ro&ect and learning about the stages of grou
formation, grou dynamics and team member roles, students discover ho( collective
action can foster a sense of community suort, (hich can alleviate ersonal feelings ofstress and tension"
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Lesson Closure
#s' the students to e-lain (hat engineering stress is and (hy engineers need to 'no( about
stress" #s' the students for different e-amles of designs that e-erience stress $bridges,benches, bicycles"""this can be &ust about anything%" #s' the students if the stress considerations
in these designs are best related to the yield strength, ultimate tensile strength or fatigue strength"
(ssessment
PreLesson #ssessment
iscussion !uestions"Solicit, integrate and summari*e student resonses to the !uestions belo("Encourage (ild ideas and ut ans(ers on the board" See Lesson Bac'ground section for ideas to
suggest if students get stuc'"
/hat do engineers mean (hen they tal' about stressH
0ave you ever e-erienced something brea'ing because of the stress you ut on itH
0o( do engineers decide if something is a good designH
PostIntroduction #ssessment
#oting"#s' a true
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Lesson !)tension (ctivities
0ave the students find an ob&ect in the room $or at home, in the case of a home(or' assignment%
that demonstrates each one of the vocabulary (ords"0ave the students (rite a fictional story about stress and strain that includes all of the vocabulary
(ords"0ave the students research different secific e-amles of (hen engineering failed in terms of
stress and strain" $4or e-amle, structures that collased during earth!ua'es or hurricanes,bridges that (ere affected by high (inds, sace structures that failed due to a lac' of gravity,
etc"% /hat did engineers have to do to fi- each situationH 0ave them create a oster about the
e-amle and include a discussion of the incident in terms if materials, stress and strain"0ave the students research three tyes of bridges" 0o( do these bridges comare and contrast to
each otherH 0o( does each bridge deal (ith comression and tension forcesH
*eferences
Shigley and 5isch'e" 5echanical Engineering +esign" @e( Kor', @K: 5cra(0ill, 331"
Lesson: Stress, Strain and 0oo'e.s La(Contributed by: U Bioengineering )ET Program, School of Engineering, anderbilt University
Summary
This lesson offers an introduction to 0oo'e.s La( as (ell as stressstrainrelationshis" Students (ill first learn the governing e!uations" Then students
(ill (or' through several e-amle roblems first individually, then as a class"
In addition, the lesson includes a t(oart associated activity" In the first art,students e-lore 0oo'e.s la( by e-erimentally determining an un'no(n
sring constant" In the second art, students (ill aly (hat they.ve learned to
create a strain grah deicting a tumor using 5icrosoft E-cel" 4inally, the
lesson includes an attached stressstrain !ui* to assess each student.s 'no(ledgefollo(ing the activities"
Engineering Connection
Engineering analysis or artial design
;ver three hundred years ago, )obert 0oo'e identified a roortionality (hich has remained a
fundamental concet to hysicists and engineers today" Though his la( (as established for thecase of srings alone, it has since been related to all materials of 'no(n surface area" The
relationshi used most readily today is the direct roortionality bet(een stress and strain"Together, civil engineers, mechanical engineers and material scientists, must carefully select
structural materials (hich are able to safely endure everyday stress (hile remaining in the elasticregion of the stressstrain curve, other(ise ermanent deformation (ill ensue" #rchitects (ho
once chose stone for its aesthetic aeal are no( choosing steel for its long term endurance" 4or
biomedical engineers, titanium is the current material of choice for its biocomatibility but mostimortantly, it.s caability to (ithstand the tensile and comressive stress of the body.s (eight" In
the attached roblem set, students e-lore alications of 0oo'e.s La( and stressstrain
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relationshis" In roblem M secifically, students aly these relationshis to the case of body
tissue, li'e a biomedical engineer (ould"
Learning Objectives
#fter this lesson, students should be able to:
1" Understand stress and strain concets and the relationshi bet(een them"
" Understand 0oo'e.s La( and aly it to analy*e srings"
J" Be able to use E-cel to ma'e a simle strain lot"
" )elate stress and strain to the engineering challenge"
Introduction/Motivation
In today.s lesson, (e (ill begin to learn about 0oo'e.s la( and then (e (ill learn ho( to alythis roortionality to body tissue" /e (ill learn e-actly (hat the terms stress and strain describe
as (ell as the relationshi bet(een them" #fter going through the lesson.s material, I (ill ass
out a handout (ith samle roblems" I (ould li'e these to be (or'ed to the best of your abilitiesindeendently firstN then (e (ill revie( the roblems as a class" #fter gro(ing familiar (ith
using the ne( e!uations, (e (ill e-lore 0oo'e.s la( in an associated activity $#lying
0oo'e.s La( to Cancer +etection% by e-erimentally determining an un'no(n roortionalityconstant" #fter e-loring 0oo'e.s la(, in the second ortion of the activity, (e (ill begin to
aly (hat (e.ve learned to develo a means of imaging body tissues and (e (ill soon be able
to detect malignant tumors6 Kou (ill ractice grahing reared data to deict cancerous tissue"
#fter (e have mastered this material, (e (ill have a !ui* on stress, strain and 0oo'e.s la("
Please ta'e careful notes and be sure to as' any !uestions you may have about the e-amleroblems (e (ill be (or'ing through"
)eferring bac' to the legacy cycle (hich (e discussed in the revious lesson, today.s lesson (illconstitute the research and revise hase" )efer bac' to your initial thoughts notes and record any
ne( information (hich (ill aly to solving the challenge" Kour goal today is to revie(, revise
and e-and you current 'no(ledge6 @o(, let.s learn ho( to detect cancer"
Lesson Background & Concepts for Teachers
Legacy cycle information:
This lesson falls into the%esearch and %evisehase of the legacy cycle" Students (ill begin to
learn the basic concets re!uired for creating a strain grah to deict cancerous tissue" 4ollo(ingthis lesson, students should revise their initial thoughts and at the conclusion of the associated
activity, students should have the s'ills necessary to &o Public (ith a solution" But before &oing
Public, students (ill comlete the attached handoutOui* Stress, Strain and 0oo'e.s La(as
art of the Test Kour 5ettle hase of the legacy cycle" This !ui* (ill offer formative assessment(hile the ne-t lesson.s &o Publichase (ill offer summative assessment"
http://www.teachengineering.org/view_activity.php?url=collection/van_/activities/van_cancer_activity2/van_cancer_activity2.xmlhttp://www.teachengineering.org/view_activity.php?url=collection/van_/activities/van_cancer_activity2/van_cancer_activity2.xmlhttp://www.teachengineering.org/collection/van_/lessons/van_cancer_lesson2/quiz_stress_strain_hookes_law.pdfhttp://www.teachengineering.org/collection/van_/lessons/van_cancer_lesson2/quiz_stress_strain_hookes_law.pdfhttp://www.teachengineering.org/view_activity.php?url=collection/van_/activities/van_cancer_activity2/van_cancer_activity2.xmlhttp://www.teachengineering.org/view_activity.php?url=collection/van_/activities/van_cancer_activity2/van_cancer_activity2.xmlhttp://www.teachengineering.org/collection/van_/lessons/van_cancer_lesson2/quiz_stress_strain_hookes_law.pdf8/13/2019 Stress and Strain Hooke's Law
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Lecture Information:
In the late 1233s, )obert 0oo'e stated that The o(er of any sringy body is in the same
roortion (ith the e-tension" Though 0oo'e.s la( has remained valid today, the (ording hasbeen corrected, relacing o(er (ith force" The la( is e-lained by a direct roortionality
bet(een a sring.s comression or e-ansion and the restoring force (hich ensues" Therelationshi is given by +, -k . ) (here )is the distance a sring has been stretch, + is the
restoring force e-erted by the sring and kis the sring constant (hich characteri*es elasticroerties of the sring.s material" This la( is valid (ithin the elastic limit of a linear sring,
(hen acting along a frictionless surface"
E-tending 0oo'e.s e-loration of srings, it becomes aarent that most materials act li'esrings (ith force being directly roortional to dislacement" But as comared to srings, other
materials ossess an area (hich must be accounted for" )elacing force (ith a measure of stress
and dislacement (ith a measure of strain, the follo(ing e-ression may be obtained, 0 , !. 1"/e (ill no( e-lore the measures of stress and strain"
Stress is a measure of average force er unit area, given by 0 , +/( (here average stress, 0,
e!uals force, +, acting over area, (" The SI unit for stress is ascals $Pa% (hich is e!ual to 1@e(ton er s!uare meter" The Psi is an alternative unit (hich e-resses ounds er s!uare inch"
The units of stress are e!ual to the units of ressure (hich is also a measure of force er unit
area"
Stress cannot be measured directly and is therefore inferred from a measure of strain and aconstant 'no(n as Koung.s modulus of elasticity" The relationshi is given by 0 , !. 1, (here 0
reresents stress, 1 reresents strain and ! reresents Koung.s modulus of elasticity" Using this
means of inferring stress, strain is a geometrical measure of deformation and Koung.s modulus isa measure used to characteri*e the stiffness of an elastic material" Strain does not carry a unit but
the units of Koung.s modulus are Pa"
Strain is characteri*ed by the ratio of total deformation or change in length to the initial length"
This relationshi is given by 1 , l/l
3(here strain, 1, is change inl
divided by initial length ,l2"The follo(ing roblems may be (or'ed indeendently and revie(ed as a class, encouraging
students to become more familiar (ith using the e!uations given above" Each student should
receive a coy of the Stress, Strain and 0oo'e.s La( Problem Set $df%"You 'ill need to S()* ALL *)%+, Useful constants that you 'ill need to -no' are in a table
belo', .assume given constants have / Significant Figures .SF0, Please also note the
relationships 'e1ve 2ust discussed given belo',5aterial
1" Steel
Koung.s 5odule: 33-138E$Pa%
" Cast Iron
Koung.s 5odule: 133-138E$Pa%
J" Concrete
Koung.s 5odule: 3"3-138E$Pa%
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F=m*a =F/A = l/l0 = E* F= -k * x
1" # JJ3 @ ball is suorted vertically by a 1"83 cm diameter steel cable" #ssuming the
cable has a length of 13"J m, determine the stress and the strain in the cable"" Consider an iron rod (ith a crosssectional area of J"91 cm that has a force of 22,M33 @
alied to it" 4ind the stress in the rod"
J" # concrete ost (ith a D3"9 cm diameter is suorting a comressive load of 9813
@e(tons" +etermine the stress the ost is bearing"
" The concrete ost in the revious roblem has an initial height of 3"DD m" 0o( much
shorter is the ost once the load is alied $in mm%H
D" # construction crane (ith a 1"83 cm diameter cable has a ma-imum functioning stress of1J9 5Pa" 4ind the ma-imum load that the crane can endure"
2" Consider 0oo'e.s La( as a simle roortionality (here 4 is directly roortional to -"Therefore, (e 'no( the force stretching a sring is directly roortional to the distance
the sring stretches" If J @ stretches a sring 1"M cm, ho( much stretch can (e e-ect
to result from a of DJ @H
M" The figure belo( sho(s a column of fatty tissue, determine the strain in each of the three
regions"
ocabuar'/#efinitions
Stress: 1" The hysical ressure, ull, or other force e-erted on a system by another" " #
load, force, or system of forces roducing a strain" J" The ratio of force to area"
Strain: 1" +eformation of a body or structure as a result of an alied force" " Stretch
beyond the roer oint or limit"%adiologist:1" # medical secialist (ho e-amines hotograhs of tissues, organs, bones for use
in the treatment of disease"
(ssociated (ctivities
#ctivity : #lying 0oo'e.s La( to Cancer +etection
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#ttachments
Stress, Strain and 0oo'e.s La( Problem Set $df%
Stress, Strain and 0oo'e.s La( Problem Set Solutions $df%
Oui* Stress, Strain and 0oo'e.s La( $df%
(ssessment
Embedded #ssessment:
The attached roblem set is to be comleted in class and may be used to gauge student
comrehension" The final !uestion of the roblem set and the alication !uestions of #ctivity offer an assessment of the students. understanding of the challenge" These !uestions should be
used as a means of testing (hether the students are alying their ac!uired 'no(ledge to(ard
solving the engineering challenge"
Post Lesson #ssessment:
The attached !ui* (ill offer a formative ostlesson assessment as art of the Test your 5ettle
hase of the legacy cycle"
*eferences
+ictionary"com" Le-ico Publishing rou,LLC" #ccessed +ecember 9, 339" $Source ofvocabulary definitions, (ith some adatation% htt:
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Engineering analysis or artial design
0oo'e.s la( defines the direct roortionality bet(een a sring.s deformation and the restoring
force that results" 5ost commonly, a derivative of 0oo'e.s la( is used in engineeringalicationsGa relationshi that directly relates stress and strain" 4or e-amle, the stressstrain
curve is commonly used by material scientists and engineers (hile selecting materials for
structures" /ithin the linear region, the sloe is defined by the Koung.s modulus of (lasticity"Civil engineers often study the stressstrain curve (hen using strain hardening and other methods
to increase the yield strength of a material" In this activity, articularly in the investigating
!uestions 2 and M, students e-lore the relationshi bet(een 0oo'e.s la( and the stressstraine!uation" In addition, students must aly their understanding of 0oo'e.s la( to create a strain
lot"
Pre)e! 7no(ledge
# basic understanding of the concets of 0oo'e.s la(, stress and strain, as resented in Lesson "
Learning Objectives
#fter this activity, students should be able to:
+escribe (hat is meant by 0oo'e.s la("
#ly 0oo'e.s la( relationshis to analy*ing tissue of a 'no(n surface area"
+eict a cancerous tumor using grahing methods in 5icrosoft E-cel"
5aterials List
Part 1:
Each lab grou needs:
hysics lab stand
meter stic'
sring $(ith hoo's%
endulum clam
slotted mass set
comuter (ith 5icrosoft E-cel $or other sreadsheet alication%
0oo'e.s La( /or'sheet, one er student
Part :
http://www.teachengineering.org/view_lesson.php?url=collection/van_/lessons/van_cancer_lesson2/van_cancer_lesson2.xmlhttp://www.teachengineering.org/collection/van_/activities/van_cancer_activity2/van_hookes_law_wkst.pdfhttp://www.teachengineering.org/view_lesson.php?url=collection/van_/lessons/van_cancer_lesson2/van_cancer_lesson2.xmlhttp://www.teachengineering.org/collection/van_/activities/van_cancer_activity2/van_hookes_law_wkst.pdf8/13/2019 Stress and Strain Hooke's Law
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Each grou needs a comuter (ith 5icrosoft E-cel and the enerating a 1+ Strain Plot
0andout" The handout has instructions secifically for E-cel, but if you ad&ust the instructions,
another sreadsheet rogram could be used"
Introduction/Motivation
0ave you ever (ondered ho( the value of the gas constant (as measured
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initial thoughts for solving the engineering challenge, students follo( stebyste instructions to
deict a cancerous tissue in a grah generated in 5icrosoft E-cel" Though students (or' in
grous, it is e-ected that they comlete their o(n activity (or'sheets" Students may discuss the!uestions but should ans(er the !uestions individually"
Before the #ctivity
Provide each lab station (ith the necessary materials"
#ssign grous of three for the activity"
5a'e coies of the 0oo'e.s La( /or'sheetand enerating a 1+ Strain Plot 0andout"
/ith the Students
1" Pass out the t(o handouts" Use the 0oo'e.s La( /or'sheet as an instructional guide(hen creating strain lots" Use the enerating a 1+ Strain Plot 0andout as an
instructional guide to the labN each student is resonsible for comleting and submitting
the analysis and alication !uestions by the end of the class eriod"
" 0ave students move into their assigned grous and go to their lab benches"
J" +irect students to follo( the (or'sheet and handout instructions" )emind them that they
may (or' together, but each student is resonsible for comleting and turning in theiro(n ans(ers and solutions"
" /hen students are ready to move on to the strain lot, have them remain in their grousNonly one grah needs to be turned in er grou" )emind them to return to their initial
thoughts notes and add any ne( notes that may hel them solve the challenge"
#ttachments
0oo'e.s La( /or'sheet $doc%
E-amle lab setu"
http://www.teachengineering.org/collection/van_/activities/van_cancer_activity2/van_hookes_law_wkst.pdfhttp://www.teachengineering.org/collection/van_/activities/van_cancer_activity2/van_generating_plot_wkst.pdfhttp://www.teachengineering.org/collection/van_/activities/van_cancer_activity2/van_hookes_law_wkst.dochttp://www.teachengineering.org/collection/van_/activities/van_cancer_activity2/van_hookes_law_wkst.pdfhttp://www.teachengineering.org/collection/van_/activities/van_cancer_activity2/van_generating_plot_wkst.pdfhttp://www.teachengineering.org/collection/van_/activities/van_cancer_activity2/van_hookes_law_wkst.doc8/13/2019 Stress and Strain Hooke's Law
14/15
14
0oo'e.s La( /or'sheet $df%
enerating a 1+ Strain Plot 0andout $doc%
enerating a 1+ Strain Plot 0andout $df%
Investigating Ouestions
0o( do 0oo'e.s la( and the stressstrain relationshi relateH /hich variables
corresondH
/hat do (e 'no( about cancerous tissue that allo(s us to use these concets to deict itH
/hat tyes of soft(are (ould be aroriate for our imagingH
Using these methods, (ill our imaging method be ainlessH /ill it be effective and
reliableH 0o( about cost effectiveH
(ssessment
Activity Embedded Assessment: The 0oo'e.s la( alication !uestions and the 1+ strain lotboth function as means of assessment" Students must first develo an understanding of 0oo'e.s
la(" Then they must relate this concet to a tissue (ith 'no(n crosssectional area" This concet
may be used to detect a cancerous tumor (here the tumor.s elastic roerties differ from that ofnormal tissue"
(ctivit' !)tensions
To e-tend the handson asect of e-loring the tissue, consider obtaining ballistic gel $such as
htt:
8/13/2019 Stress and Strain Hooke's Law
15/15
15
+ictionary"com" Le-ico Publishing rou,LLC" #ccessed +ecember 9, 339" $source of
vocabulary definitions, (ith some adatation%
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