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Bones ADEPT Module - Oakland Unified School District

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Bones ADEPT Module - Oakland Unified School District Powered By Docstoc
					Disseminating information
                                 University of California Berkeley
                                      Applied Design Engineering Project
                                                    Teams
   into our community
                                                   (ADEPT)
                                      ADEPT is funded by a grant from the National Science
                                                          Foundation


              <Bone Composition, Structure, and Mechanics>
Objective/Purpose:
Students will learn about the concepts of
loading, stress, and strength in the context of           Prep—Time: A few hours-a day
bone and the skeletal system. Students will
understand bones in our body are under                    Lesson Time:          Two 60-90 min
various types of loading. Excessive stresses in           sessions
the bone can cause it to break or fracture.
Students will

1) understand how structures of bone give rise
to its mechanical properties and functions;
                                                          Material List:
2) learn the types of loading in the body and
                                                          Per Student—
how bone can fracture under loading.
                                                               Carrot sticks
                                                               Raw Sphaghetti
                                                               Notebook to record what they learned
Topic:
The musculoskeletal system, anatomy and                   Per Group—
physiology of bone, loading, stress, strength,                 Scissors, tape, paper
and fracture                                                   Bubble tea straws
                                                               Regular flexi straws
                                                               Paper clips
                            th   th
Grade Level:                6 -8 Grades

                                                          Per Class—
Pre-Requisites:                                                Diagrams and/or models of bone
                                                               T-bone from the meat market
                                                               Cleaned chicken bones
1. Basic knowledge about the muscuoloskeletal
system (as presented in a standard science
textbook on general biology or human
physiology)

2. Proficiency with finding areas and
calculations involving multiplication and division




Lesson Process Summary:
 Preparation For The Lesson

   1. Prepare materials on the material list
   Note: T-bone and chicken bones can be purchased from the local meat store.
   2. Preparation of chicken bones
(Adapted from http://www.ucmp.berkeley.edu/museum/events/bigdinos2005/turkey.html)

Cleaning: Skin and strip the chicken thighs. Put the bones into a pot of water. Cover and boil the
bones so any remaining meat falls off (usually two hours of at a light boil). Let the bones cool in
the air for a few minutes or run them under cold water. Scrub the bones to remove all the
remaining meat and cartilage.

Degreasing: Soak the bones in soapy water to help degrease them if needed.

Bleaching: Soak the bones for a few hours in ordinary drugstore-variety 3% hydrogen peroxide
($0.99 from Walgreens, Kmart, etc.).

Drying: Put a couple of paper towels on a plate, put the bones on the plate, and set them in the
sun for a few hours.



    Safety Tips
           Do not put the bone in mouth
           If bones are not thoroughly cleaned,
            please handle with gloves


Initiating The Class

   1. Introduce the module: the purpose is to learn about the structure and function of bone.
       Hand out prepared chicken bones. Inspire the students’ curiosity by asking them to think
       about how strong bone might be, and how bone
       delivers its functions - support, movement,
       protection of internal organs, making blood, and      Vocabulary:
       storage calcium in the body..
   2. Then ask the class what makes bone strong and                Tissue
       tough? Think about the type of forces our leg               Cancellous/trabecular/spongy
       bones need to support, or how much weight we                   bone
       can carry in our arms. What happens when you                Cortical/Compact bone
       bone breaks? If anyone has ever broken a bone               Epiphysis
       and ask him/her to share the experience.                    Epiphyseal plate/line
   3. Administer the pretest “Bone structure and                   Diaphysis
       composition Pretest” to assess what the students            Epiphyseal plate/line
       already know and want to learn.                             Bone cell
                                                                   Osteon
Procedures For Session                                             Periosteum
                                                                   Haversian canal
                                                                   Lacuna
1. Getting to know bones – structure and                           Lamella
composition                                                        Stress
                                                                   Strain
   1. Divide the students into groups of two.                      Strength
   2. Ask each pair to come up with the best set of                Fracture
       descriptions for the assigned terms from “Bones
      Activity Sheet 1.” For each term, students are asked to describe its location, geometry,
      and function. Students will consult text books, models, and internet sources. A list of
      “Definitions of terms” along with three figures “Bone structure figures” are provided for
      your reference. You may choose to share these with your students.

2. How bones break?

  1. Explain the purpose is to learn about loading, and how material properties and behavior
     such as stress, strength, and fracture.
  2. Hand out “How Bones break?” and explain the procedures for this activity.
CA Science and Math Standards:
ID those standards met by this module
http://www.cde.ca.gov/be/st/ss/index.asp

Grade 7: Science Standards
Physical Principles in Living Systems
6h. Students know how to compare joints in the body (wrist, shoulder, thigh) with structures used in
machines and simples devices (hinge, ball-and-socket, and sliding joints).
i. Students know how levers confer mechanical advantage and how the application of this principle applies
to the musculoskeletal system.

Investigation and Experimentation
7a. Select and use appropriate tools and technology (including calculators, computers,
balances, spring scales, microscopes, and binoculars) to perform tests, collect data, and display data.
b. Use a variety of print and electronic resources (including the World Wide Web) to collect information
and evidence as part of a research project.
c. Communicate the logical connection among hypotheses, science concepts, tests conducted, data
collected, and conclusions drawn from the scientific evidence.
d. Construct scale models, maps, and appropriately labeled diagrams to communicate
scientific knowledge (e.g., motion of Earth’s plates and cell structure).

Grade 8: Science Standards
Forces
2a. Students know a force has both direction and magnitude.




Grade 6 : Math Standards
Number Sense
2.3 Solve addition, subtraction, multiplication, and division problems, including those arising in
concrete situations, that use positive and negative integers and combinations
of these operations.

Measurement and Geometry
1.0 Students deepen their understanding of the measurement of plane and solid shapes and use
this understanding to solve problems:
1.1 Understand the concept of a constant such as ; know the formulas for the circumference
and area of a circle.
1.2 Know common estimates of  (3.14; 22⁄7) and use these values to estimate and calculate
the circumference and the area of circles; compare with actual measurements.
1.3 Know and use the formulas for the volume of triangular prisms and cylinders (area of base ×
height); compare these formulas and explain the similarity between them and the formula for the
volume of a rectangular solid.

2.6 Indicate the relative advantages of exact and approximate solutions to problems
and give answers to a specified degree of accuracy.
2.7 Make precise calculations and check the validity of the results from the context
of the problem.
3.0 Students move beyond a particular problem by generalizing to other
situations:
3.1 Evaluate the reasonableness of the solution in the context of the original situation.
3.2 Note the method of deriving the solution and demonstrate a conceptual understanding
of the derivation by solving similar problems.
3.3 Develop generalizations of the results obtained and the strategies used and apply
them in new problem situations.
Grade 7: Math Standards
Measurement and Geometry
2.1 Use formulas routinely for finding the perimeter and area of basic two-dimensional
figures and the surface area and volume of basic three-dimensional figures, including
rectangles, parallelograms, trapezoids, squares, triangles, circles, prisms, and cylinders.

Mathematical Reasoning
1.0 Students make decisions about how to approach problems:
1.1 Analyze problems by identifying relationships, distinguishing relevant from
irrelevant information, identifying missing information, sequencing and
prioritizing information, and observing patterns.
1.2 Formulate and justify mathematical conjectures based on a general description
of the mathematical question or problem posed.
1.3 Determine when and how to break a problem into simpler parts.
2.0 Students use strategies, skills, and concepts in finding solutions:
2.1 Use estimation to verify the reasonableness of calculated results.
2.2 Apply strategies and results from simpler problems to more complex problems.
2.3 Estimate unknown quantities graphically and solve for them by using logical
reasoning and arithmetic and algebraic techniques.
2.4 Use a variety of methods, such as words, numbers, symbols, charts, graphs, tables,
diagrams, and models, to explain mathematical reasoning.
2.5 Express the solution clearly and logically by using the appropriate mathematical
notation and terms and clear language; support solutions with evidence in both
verbal and symbolic work.
2.6 Express the solution clearly and logically by using the appropriate mathematical
notation and terms and clear language; support solutions with evidence in both verbal
and symbolic work.
2.7 Indicate the relative advantages of exact and approximate solutions to problems and
give answers to a specified degree of accuracy.
2.8 Make precise calculations and check the validity of the results from the context of the
problem.
3.0 Students determine a solution is complete and move beyond a
particular problem by generalizing to other situations:
3.1 Evaluate the reasonableness of the solution in the context of the original situation.
3.2 Note the method of deriving the solution and demonstrate a conceptual
understanding of the derivation by solving similar problems.
3.3 Develop generalizations of the results obtained and the strategies used and apply
them to new problem situations.
Definition of terms (For teacher’s reference)

List A: Bone at the macro-scale (Figure 1)

Articular cartilage— thin layer of soft tissue which covers the bony ends of long bones and
provides the articular or low-frictional surface.
Cancellous bone (trabecular bone)—porous bone made of bony struts (trabeculae), a.k.a.
spongy bone, and filled with bone marrow. Its structs brace the compact bone shell, help to
support load, reduce weight, and allow residence of marrow, blood vessels and nerves.
Epiphyseal plate/line—epiphyseal line is the line that marks the site of the epiphyseal plate, and
separates the epiphysis and the diaphasis. Epiphyseal plate is the cartilage at the site of bone
production during growth.
Compact Bone—nonporous bone that consists largely of concentric bone layers (osteons and
lamellae).
Epiphysis—enlarged bone ends of long bones, covered by articular cartilage on the surface and
separated from the diaphysis by the epiphyseal growth line; help to support load and joint
articulation.
Diaphysis—the shaft, or long central region of the bone, containing the medullary cavity and
helps to support load.
Periosteum—outer surface membrane of bone. Thick outer layer is dense fibrous irregular
connective tissue and contains blood vessels and nerves. These fibers merge with
tendon/ligament/joint capsules and anchor them to bone. The inner layer consists of cell and
sustains adult bone growth.
Endosteum—a thin layer of connective tissue which lines the surface of the medullary cavity of
long bones.
Medullary cavity—central cavity lined with thin cellular membrane called endosteum and filled
with bone marrow, blood vessels and nerves.


List B: Bone at the micro-scale (Figure 2, 3)

Osteon— central canal and the concentric lamellae encircling it, occurring in compact bone. Also
called haversian system.
Haversian canal—Any of various canals in compact bone through which blood vessels, nerve
fibers, and lymphatics pass.
Volksmann’s canal—canals in compact bone perpendicular to the Haversian canals and
connects them horizontally; similar to Haversian canals, they house blood vessels, nerve fibers,
and lymphatic vessels.
Lacuna—round spaces in compact bone which houses the bone cells.
Lamella—a thin plate, scale, membrane, or layer, as of bone, tissue, or cell walls.
Osteocyte—mature bone cell which resides in the lacunae and maintain bone.
Osteoblast—cell with single nucleus which build bone.
Osteoclast—cell with multiple nuclei which destroys old bone.
Bone structure figures


Long bone cross section on the macro scale




http://137.222.110.150/calnet/musculo/page3.htm




Bone structure figures
3-D model of long bone showing microscopic
structures




www.jpmcgowandesign.com




Bone structure figures
2-D stained section of long bone cross section
showing bone microstructures




www.erl.pathology.iupui.edu
Name:________________________               Date:_______________ Period:_____________


Bones activity sheet 1

Directions: For each term:

          1) Draw a detailed sketch of it

          2) Describe the location, geometry, and function in bone. Think about how the structure

might give rise to its function in the bone.



Example:



             Blood vessel (in bone)

Sketch:




Location, Geometry, and Function:__Long,         thin, tubular, look like treebranches;_____

          Blood vessels are   found covering the outersurface of the bone, and also in

the___ central cavity of the bone.__________________________________________________

          Blood vessels transport blood containing oxygen and nutrients to the bone

and__ carry away CO2 and metabolic waste products form the

bone._____________________

Now you try it…
             Articular cartilage

Sketch:




Location, Geometry, and Function:_________________________________________

_____________________________________________________________________________

_____________________________________________________________________________

_____________________________________________________________________________

_________________________________________________________



             Cancellous/Trabecular/Spongy bone

Sketch:




Location, Geometry, and Function:_________________________________________
             Compact/Cortical bone

Sketch:




Location, Geometry, and Function:_________________________________________

_____________________________________________________________________________

_____________________________________________________________________________

_____________________________________________________________________________

_________________________________________________________



             Epiphyseal plate/line

Sketch:




Location, Geometry, and Function:_________________________________________

_____________________________________________________________________________

_____________________________________________________________________________

_____________________________________________________________________________

_________________________________________________________
             Epiphysis

Sketch:




Location, Geometry, and Function:_________________________________________

_____________________________________________________________________________

_____________________________________________________________________________

_____________________________________________________________________________

_________________________________________________________



             Diaphysis

Sketch:




Location, Geometry, and Function:_________________________________________

_____________________________________________________________________________

_____________________________________________________________________________

_____________________________________________________________________________

_________________________________________________________
             Periosteum

Sketch:




Location, Geometry, and Function:_________________________________________

_____________________________________________________________________________

_____________________________________________________________________________

_____________________________________________________________________________

_________________________________________________________



             Medullary cavity

Sketch:




Location, Geometry, and Function:_________________________________________

_____________________________________________________________________________

_____________________________________________________________________________

_____________________________________________________________________________

_________________________________________________________
             Osteon

Sketch:




Location, Geometry, and Function:_________________________________________

_____________________________________________________________________________

_____________________________________________________________________________

_____________________________________________________________________________

_________________________________________________________




             Haversian canal

Sketch:




Location, Geometry, and Function:_________________________________________

_____________________________________________________________________________

_____________________________________________________________________________

_____________________________________________________________________________

_________________________________________________________
             Lamella

Sketch:




Location, Geometry, and Function:_________________________________________

_____________________________________________________________________________

_____________________________________________________________________________

_____________________________________________________________________________

_________________________________________________________



             Lacuna

Sketch:




Location, Geometry, and Function:_________________________________________

_____________________________________________________________________________

_____________________________________________________________________________

_____________________________________________________________________________

_________________________________________________________
             Bone cells

Sketch:




Location, Geometry, and Function:_________________________________________

_____________________________________________________________________________

_____________________________________________________________________________

_____________________________________________________________________________

_________________________________________________________
Name:________________________              Date:_______________ Period:_____________


Bone Structure and Composition                                               Pre/Post-test
0. In 50 words or less, tell us what else you know about bones, or what questions or concerns
you have about them. You may use drawings to help you illustrate.




1. What are the functions of the skeletal system (There are five total)?



2. (True/False) The two types of bones found in the body are compact bone and spongy bone.


3. The cartilage that lines the surface of your joints are called

a) articular/hyaline cartilage             b) elastic cartilage              c) fibrocartilage


4. (True/False) Bone provides attachment site for tendons, ligaments, and muscles which connect
the bones and to help the body move.


5. ________________________is the soft tissue found in the center of bones. It is the place
where most new blood cells are produced.


6. (True/False) A joint is where two bones come close together.


7. Approximately how many bones are there in the human skeletal system?

a) 126           b) 26            c) 206            d) 96           e) 596
9. Two minerals that make up the nonliving part of bones are

a) sodium and chlorine
b) calcium and iron
c) magnesium and phosphorus
d) calcium and phosphorus


10) The longest bone in the body is the

a) vertebra     b) collarbone               c) femur               d) breastbone


11) An example of a ball-and-socket joint is the

a) shoulder     b) neck                     c) elbow               d) knee


12) (True/False) The basic structural unit of compact bone consist of a central canal and
concentric rings around it called lamella.

13) Bone cell which lives in the round spaces and sustains bone growth is called

a) osteocyte              b) osteoblast            c) osteoclast             d) red blood cell


14) Bone cell which builds bone is called

a) osteocyte              b) osteoblast            c) osteoclast             d) red blood cell


15) Bone cell which destroys old bone is called

a) osteocyte              b) osteoblast            c) osteoclast             d) red blood cell


16) (True/False) Bone consists of a solid block of wood in side and coated with a hard fibrous
sheath.

17) (True/False) The function of the trabecular bone is to reduce weight, help support load, and
contain marrow and blood vessels.

18) (True/False) Bone is a type of hard tissue in the body.
19) Fill in the various part of a long bone
Name:________________________              Date:_______________ Period:_____________


Answer Key                        Bone Structure and Composition
0: In 50 words or less, tell us what else you know about bones, or what questions or concerns
you have about them. You may use drawings to help you illustrate

1. What are the five functions of the skeletal system?

         1) Support the body
         2) Allows movement by connecting muscles and tendons
         3) Makes blood
                      2+
         4) Stores Ca and other minerals
         5) Protect internal organs

2. (True/False) The two types of bones found in the body are compact bone and spongy bone.


3. The cartilage that lines the surface of your joints are called

a) articular/hyaline cartilage             b) elastic cartilage               c) fibrocartilage


4. (True/False) Bone provides attachment site for tendons, ligaments, and muscles which connect
the bones and to help the body move.


5. Bone marrow is the soft tissue found in the center of bones. It is the place where most new
blood cells are produced.


6. (True/False) A joint is where two bones come close together.


7. Approximately how many bones are there in the human skeletal system?

a) 126           b) 26            c) 206            d) 96           e) 596

9. Two minerals that make up the nonliving part of bones are

a) sodium and chlorine
b) calcium and iron
c) magnesium and phosphorus
d) calcium and phosphorus


10) The longest bone in the body is the

a) vertebra      b) collarbone             c) femur                 d) breastbone


11) An example of a ball-and-socket joint is the

a) shoulder      b) neck                   c) elbow                 d) knee
12) (True/False) The basic structural unit of compact bone consist of a central canal and
concentric rings around it called lamella.

13) Bone cell which lives in the round spaces and sustains bone growth is called

a) osteocyte             b) osteoblast            c) osteoclast           d) red blood cell


14) Bone cell which builds bone is called

a) osteocyte             b) osteoblast            c) osteoclast           d) red blood cell


15) Bone cell which destroys old bone is called

a) osteocyte             b) osteoblast            c) osteoclast           d) red blood cell


16) (True/False) Bone consists of a solid block of wood in side and coated with a hard fibrous
sheath.

17) (True/False) The function of the trabecular bone is to reduce weight, help support load, and
contain marrow and blood vessels.

18) (True/False) Bone is a type of hard tissue in the body.
19) Fill in the various part of a long bone




         Epiphysis



                                                 Spongy bone



         Diaphysis



                                                Compact bone




                                              Articular cartilage
Bone Fracture
         Fractures are breaks in the bone that are often caused by a great force as a result from
a sudden blow or a fall. A broken bone, depending on the extent of the injury, can be very painful,
and the person can no longer perform normal functions.
         A fracture can range from a simple hairline fracture (a crack that may not run through the
entire bone) to a compound fracture (part of the broken bone may protrude through the skin).
Most fractures occur in the arms and legs.
         A stress fracture (a.k.a. fatigue fracture) is a crack caused by forces that are much lower,
but happen repetitively for a long period of time. Stress fractures often occur in the foot after
training for basketball, or other sports.
         However an intact unbroken bone can fail too. For example, in kids whose bone is not
fully matured and the bone is not as brittle as adult bone, the bone may bend instead of break
under loading. This jeopardizes one of bone’s functions of supporting the body.




           If you ever gnawed on a piece of chicken bone, you would know that bone is very hard
(5x harder then steel) and very strong. Bone is made primarily of minerals called hydroxyapatite
(Ca10(PO4)6(OH)2) and a fibrous protein called collagen. The mineral gives bone crush
resistance. Think of minerals as solid rocks. The protein provides the bone with strength and
flexibility. Think of proteins as tough fabric you can stretch very hard on.
           However, these are not the only reasons why bone is strong. What makes bone so strong
to provide important functions for the body? What type of load or forces might cause bone to
fracture? How does the bone fracture? You will know the answers by the end of this lesson.
How bone breaks?
Everyday our bodies exert all types of forces on the bones of our skeleton. Let us take a closer
look at our lower leg bones—the tibia and the fibula below. The tibia is the thicker of the two lower
leg bones. We will use the tibia to illustrate forces on the bone.




                         http://homepage.mac.com/myers/misc/bonefiles/tibia.gif


1.       Get up and try it out. What type of forces does your leg bones typically sustain?
Illustrate with drawings 3 types of forces and the associated activity, for example jumping
or hanging causing the forces. Use arrows to point in the direction of the force and where it is
acting on the bone. See example above.




2.       With a partner, try the following. We now use a carrot to model the tibia.
        Pull on it. Does it break? If so, how? This pulling is a type of load called tension.




        Push on the two ends. Does it break? If so, how? This pressing is a type of load
         called compression.
       Bend the two ends toward the middle section. Does it break? If so, how? Draw the
        broken ends in the space provided below. This type of load is called bending.




       Grab the two ends and twist it. Does it break? If so, how? Draw the broken ends
        in the space provided below. This twisting is a type of load called torsion.




3.      From the experiment above, what conclusion(s) can you make about the strength
of the carrot?




4.     Of course real bone is much stronger material than carrot. Recall that bone is made up of
hydroxyapatite and collagen together to give the maximum strength. Real bone is strongest
when been compressed. Can you think of why?




5.      Strength is a property of the material, which determines how much force is required to
break the material of a given dimension. Strength of materials depends on the make-up or
composition of the material. However given the same material, you can change how easily it
breaks too. Try pulling on one strand of spaghetti with the same force you were applying
on the one strand. Does it break? Why?
6.     Now grab a handful of spaghetti to form a bundle and pull with the same force as
you were applying before on the single strand. Does it break? Why?




7.       When you pull on something with big enough force, it will break. This includes a thick
bundle of spaghetti. What determines the strength of a material, however, is not how hard you
pull, but the stress that the material feels. Stress is defined as:

                                  Stress = Force
                                           Area


           Force                                             Force

                                       Area




You can think of stress as force supported by a unit of area, or force divided by the area of
material supporting the force. Which of the cylinders above is under less stress? Why?




The column on the left has a larger area (shaded region) supporting the force than the column on
the right. Therefore, given that the two cylinders are made from the same material, and the same
amount of force is applied to the two cylinders, the left cylinder is under less stress than the right.

8.      Some materials, like elastic rubber bands, can ―give in‖ to force by stretching a lot before
breaking. The stretching or shortening of the material in response to the applied load is called
deformation. The applied force is directly related to the deformation in the material by a
constant, k, according to the following equation (think of a spring):

                                  Force = k * Deformation

Other ways of writing this is:
                                     Deformation = Force
                                                   k
or


                                     k=           Force____
                                                Deformation

9.     We call k the stiffness of the material. Hint: the greater the compressive k, the less it
would deform under a given compressive force. Now rank the following materials in order of
decreasing compressive k (1=most stiff, 5=least stiff in compression).


Carrot               Bone                      Plastic rod                  Steel rod             Bannana


There are a couple of ways to think about this question. One way is to take a look at the last
equation above. Essentially the question is asking: if you try to stretch the material with a given
force, is it going to deform a lot or a little? If it will deform a lot, then k is small for the material.
The material is not very stiff (or it is flexible). If it will deform a little, then k is large for the material.
We say the material is relatively stiff.




If you mentioned that bone has a very complex structure—you’ve got it right! Structures in the
material can help to reinforce the material and makes it stronger! Take a plastic straw; bend it to
feel how stiff it is. Now cut along its length to flatten out the structure; try bending it again. How
easily does it fail compared to before? Why?


The tubular structure of the same material is stiffer than the flattened sheet of the same
material. Can you explain why?




Oftentimes, materials are stronger if you combine two or more materials. These materials are
called composite materials. Let’s consider your straw again. Given what you have learned
about materials and what make them strong, how would you best reinforce the straw to
give it the highest strength? Describe and sketch your design.
Is bone a composite material? Explain.




Some relatively strong materials may not break at first. Try breaking a paper clip by bending it. If
you bend it over and over again, however, eventually it will break. How many times of bending
does it take to break a paper clip?

When the material fails from repeated loading, it is called fatigue failure. Repeated loading is
what bones in our body experiences during walking, running etc. Therefore fatigue failure can
happen in bone. A fracture (stress fracture) can result from a hairline fracture of the bone that has
been subjected to repeated loading and finally break.




References

http://www.healthsystem.virginia.edu/uvahealth/adult_pmr/sports.cfm
Name:________________________              Date:_______________ Period:_____________


How Bone Breaks?                                                              Pre/Post Test
1. (True/False) A sudden blow or fall during physical activity can often cause a fracture in the
bone.


2. (True/False) When material fail from repeated loading, it is called fatigue failure.


3. All of the following are types of fracture that can occur in bone except:

a) Hairline fracture      b) compound fracture           c) stress fracture    d) blunt fracture


4. All of the following are types of load on bone in our body except:

a) Torsion       b) Bending          c) Shrinking         d) Tension           e) Compression


5. (True/False) Strength is a property of the material, and depends on the make-up of the
material.


6. (True/False) Glass is an example of a brittle material.


7. (True/False) If a material is relatively stiff, for example, bone, then it does not easily deform
when you apply a certain amount of force on it.


8. Which of the cylinders below can sustain more force and why?

a)            Force                                 b)            Force
9. Which of the cylinders below can sustain more force and why?

a)               Force                             b)            Force




10) Calculate the amount of stress in the cylindrical shell structure if it needs to support 100 lbs of
force. Use the dimensions given in the diagram below.



                   5 inches

                   4 inches                                  Stress = Force
                                                                     Area
Name:________________________              Date:_______________ Period:_____________




How Bone Breaks?                                Pre/Post Test Answer Key

1. (True/False) A sudden blow or fall during physical activity can often cause a fracture in the
bone.


2. (True/False) When material fail from repeated loading, it is called fatigue failure.


3. All of the following are types of fracture that can occur in bone except:

a) Hairline fracture      b) compound fracture           c) stress fracture    d) blunt fracture


4. All of the following are types of load on bone in our body except:

a) Torsion       b) Bending          c) Shrinking         d) Tension           e) Compression


5. (True/False) Strength is a property of the material, and depends on the make-up of the
material.


6. (True/False) Glass is an example of a brittle material.


7. (True/False) If a material is relatively stiff, for example, bone, then it does not easily deform
when you apply a certain amount of force on it.


8. Which of the cylinders below can sustain more force and why?

a)            Force                                 b)            Force
9. Which of the cylinders below can sustain more force and why?

a)               Force                             b)            Force




10) Calculate the amount of stress in the cylindrical shell structure if it needs to support 100 lbs of
force. Use the dimensions given in the diagram below.


                   5 inches

                   4 inches                                  Stress = Force
                                                                     Area




Force = 100 lbs

Notice that Stress is only dependent the area upon which force is exerted.
Therefore we only need to calculate the base area of the cylinder – a circle.

Recall area of a circle = r2
       Area of the outer circle = (5/2)2
       Area of the inner cylinder = (4/2)2
Area of shaded region = Area of the outer cylinder – Area of the inner circle
Plug in formula above for Force and Area of the shaded region to calculate the
stress on the cylindrical shell.

				
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