Some additional online quizzes...

You can complete these quizzes to help you study. Remember that completing the quizzes does not replace studying from your notes!

Section 5.1 Quiz

https://sciencesource.pearsoncanada.ca/quizzes/quiz_05_1mM3MX.htm

Section 5.2 Quiz

https://sciencesource.pearsoncanada.ca/quizzes/quiz_05_2zKqKR.htm

Chapter 5 Review Quiz

http://wps.pearsoned.ca/ca_school_ontarioscience_7-8/102/26140/6692002.cw/content/index.html

Chapter 5 Matching Terms

https://sciencesource.pearsoncanada.ca/resources/gr7_matchquiz_ch05/

Chapter 5 Labeling Practice

https://sciencesource.pearsoncanada.ca/resources/gr7_labelquiz_ch05/

5.1 Crossword

https://sciencesource.pearsoncanada.ca/puzzles/puzzle_05_1/

5.2 Crossword

https://sciencesource.pearsoncanada.ca/puzzles/puzzle_05_2/

Elements of Design (Textbook Information)

I had a request to post the elements of design questions. 

This is the text from our textbook.


Elements of Good Design

All structures are designed and built for specific functions. How
do you know if your structure has a good design? To find out,
ask yourself these questions as you are designing and building.

Does my design link the structure to its function?

Sometimes this question is not as easy to answer as it might
seem. Designing a simple structure for a simple function is quite
easy. For example, a coffee table is a small structure designed to
support small loads and add to the décor of a home. Designing a
structure to fit a more complex function, such as a machine to
pick peaches without bruising them, is much more complicated.

Can my design withstand the forces that the
structure will encounter?

Good designers consider both the static and the dynamic loads
that might affect the structure. Structures with similar forms
may serve different functions. A coffee table made from
pressed wood might withstand the forces in a home with a
small child. A delicate glass coffee table may not.

Is my design easy to build with the materials 
I want to use?

If you were asked to build a coffee table out of wood, another
out of glass, and a third out of metal, would that affect your
designs? Of course it would. Some materials are easier to cut
and join together than others. Some materials can be bent
while others cannot.

Is my design ergonomic?

Ergonomics is the science of designing equipment that people
can use more efficiently and safely. An ergonomic structure
minimizes stress on the user’s body. The design and layout of
office furniture and supplies often involve ergonomics. People
who do repetitive jobs may suffer from repetitive strain injury
if they are not using proper equipment and techniques to
reduce the stress on their bodies (Figure 5.20).

Is my design aesthetically pleasing?

If you could choose any coffee table for your home, which
would you choose? You might like either of the two shown in
Figure 5.22, or you might hate both! All coffee tables have the
same function, so why are there so many different forms?
The main reason is that different people find different forms
and shapes more aesthetically appealing than others. Some
people find symmetry appealing. Symmetry is a balanced
arrangement on opposite sides of a structure. Others may enjoy
something a little more unusual. Some may find a particular
material more appealing because of its texture or colour. No
matter what the structure, it will not be equally appealing to all
people because aesthetic appeal is highly personal.

Do I want my design to be symmetrical? 

You may have noticed that many structures seem to have equal
halves. This means that they are designed symmetrically. There
are a number of reasons for this. Humans tend to like things to
look symmetrical. It is aesthetically pleasing. Symmetrical
things are usually also stable. Think about the wobbly chair.
The wobble is caused because one of the chair legs is not the
same length as the others. Symmetrical structures can spread
the load more evenly. Humans and many other animals are also
symmetrical in form (Figure 5.23).

Prototypes

When you are happy with the answers to all of these questions,
you may have a good design. However, this does not mean that
it is the best design possible. Something that looks fine on
paper may not be as practical when you are using it. You often
cannot know everything you need to know until you test your
design. This is why manufacturers often make prototypes of a
structure before they commit to a design.

A prototype is a model used to test and evaluate a design.
If you are designing something really big, test a smaller
prototype as much as possible before building the full-scale
version. You should also test prototypes if you are designing
something that you want to produce in large quantities. It
would be awful to manufacture a million new pens and then
find out that they are uncomfortable to hold!

Centre of Gravity Toy Follow-up questions Due November 13th

Centre of Gravity Toy Assignment

Please submit detailed answers to the following questions along with your balance toy and all rough copies of your project.

Your answers should be neatly TYPED and submitted in a polished draft.

1.     How did you determine the centre of gravity of your toy?

2.     What was the most challenging part of making your toy? Explain your answer in detail.

3.    How does the shape of your toy relate to what you learned about structures and stability in chapter 5? 

Chapter 5 Test Study Guide

Review the following terms and concepts to help you prepare for the chapter 5 test.

Please make use of your classroom notes, the textbook, as well as your completed worksheets from your package.

□  arch □  beam □  box beam □  cantilever □  centre of gravity □  column □  corrugated cardboard □  corrugated metal □  ergonomics □  failure □  fatigue □  girder □  I-beam □  product recall □  prototype □  stability □  stress □  structural components □  structural failure 1. What are the strongest structural shapes? (p. 131) 2. Become familiar with the 8 structural components on page 132. 3. Review how to determine the centre of gravity of a structure. 4. What makes a structure stable? (p. 133-134) and review the package worksheets. 5. Review product recalls. (p. 136) 6. What are the 7 elements of good design? (p. 141-143)

□  structural fatigue □  structural stress □  symmetry

Chapter 5 Test Dates

7A, 7B, 7C, AND 7D will have their chapter 5 test on Thursday November 13th.
7E will have their test on Wednesday November 12th.

A study guide will follow shortly.

Section 5.1 Structures Notes

Good design, materials, and construction make structures stable and strong

·         Stability and strength depends on a structure’s material as well as the fasteners used (bolts, welds, wire, thread, glue, etc.)

·         Stability: the ability of a structure to maintain or resume its position when an external force has been applied to it.

Structural Strength

·         Some structures have stood for thousands of years e.g., the Coliseum in Rome, the Pyramids in Egypt

Structural Shapes

·         Some structural strength comes from the shapes used in its design

·         Triangles are stronger than squares and rectangles

·         Triangular prisms are stronger than square and rectangular prisms

Structural Components

·         Arches, beams and columns are common structural components that are used often because they can add strength and are attractive

·         The components can be used alone or in combination e.g., arches and columns

·        Please complete the structural components worksheet

Structural Materials

·         It is important to choose appropriate materials when designing and building structures; designers should consider strength, attractiveness, cost, etc.

Centre of Gravity

·         Centre of gravity: the point at which a body’s mass is concentrated – the body is equally balanced in all directions at this point

o   For example, when you balance a ruler on your finger, the centre of gravity is the middle of the ruler because each side of the ruler is symmetrical

·         Every structure has a centre of gravity; the location of the centre of gravity helps determine how stable the structure is

o   For example, a stool is a stable structure; however when a person sits on the stool, the centre of gravity is higher so the stool is more likely to tip over

Stability

·         Stability depends on materials, construction techniques and centre of gravity

o   E.g., a table can have a high centre of gravity, but it can be stable if it has four legs far apart

·         Form can also affect stability; a solid structure with a high centre of gravity may be less stable than a frame table is

·         Some structures are designed to be unstable; e.g., front ends of cars are meant to collapse easily in a collision

When Things Go Wrong

Structural Stress and Fatigue

·         Poorly built structures may not be able to withstand forces

·         Large internal and external forces may weaken the structure

·         This can result in structural stress

·         A bend in a shelf is an example of this stress; the shelf may go back to its original shape when the load is removed

·         Permanent changes occur when the shelf cannot withstand the stress; e.g., cracking. This is called structural fatigue.

Structural Failure

·         Ignoring structural fatigue can lead to structural failure; this is the breakdown of a structure due to the internal and external forces acting on it

·         Structures often show signs of structural fatigue by bending and cracking before finally failing and collapsing.

Product Recalls

·         Public recall of seriously flawed products sold to consumers by manufacturers

·         Examples:

o   high levels of paint in children’s toys

o   choking hazards in products for children

o   overheating batteries, poor safety features

o   cars with faulty parts or design

Designing for Safety Sheet Answers

Designing for Safety

In this section, you will learn about some of the ways in which designers plan safety into structures and the factors they consider when designing and monitoring them.

Risk Management

No one can design a structure to be 100% failure proof. The materials may wear down over time. A person may use it incorrectly and break it. Unexpected forces might come into play.

Engineers use the techniques of risk management to reduce the risk of failure as much as possible. They deal with known risks in one of three ways:

Ignore the risk

Avoid the risk

Design for the risk

When a risk is highly unlikely to occur, it can be ignored E.g., an elephant sitting on a classroom chair.

Building a bridge with no supports in the water is a way to avoid the risk of boats colliding with the bridge supports.

When designers design for risk they often over-compensate for the various risks. They often make the structure stronger than it really needs to be; e.g., stronger bridge supports in the water in case of a boat collision.

They also build in back-up systems and warning systems that may use sensors

Designing for Loads

When designing a structure, the designers must calculate the load it will support. They design the chair to support more than itself plus the maximum occasional load.  Some structures have warning notices about the maximum load they are designed to support e.g., an elevator.

Designing for Safety

The Ontario Building code gives minimum standards for all aspects of building, including load bearing design and materials. This assures the public of a certain level of safety.

The Ontario Fire code is a law in Ontario that states that every home in Ontario must have working smoke alarms on every floor and outside sleeping areas. Properly installed smoke alarms can warn people to get out of a burning building. This reduces the number of fire related injuries and deaths.

Designing for Efficiency

Something described as “efficient” operates well without a waste of time, effort or expense E.g., if two students build bridges that can support the same load, the bridge that uses the lesser amount of materials (usually by weight) is considered more efficient

Sensors

A sensor is any device that can detect or measure real- world conditions.  Different sensors can detect heat, light, pressure, or sound; as well as changes in the amounts of these things.

Make a list of the sensors found in your home:

Smoke detectors, carbon monoxide detectors and thermostats

How are sensors used in entertainment?

Wii, and Xbox connect, dance video game. 

Where are motion detectors used?

Automatic doors, automatic lights, automatic taps, motion sensors for alarms, reverse sensors, garage door sensor,

How do engineers use sensors to make people safe?

Security cameras that sense noise, traffic lights, vibration sensors for weaknesses in the building. 

Chapter 4 Test Dates

Class 7A, 7C, 7E, 7D will have their test on Wednesday October 15th
Class 7B will have their test on Tuesday October 14th

Links to Review Activities

You can complete these quizzes to help you study. You may notice an error or two; don't focus on the errors. Please note: Completing these activities does not replace studying your notes. I suggest you quiz each other on key information you learned in this chapter.

Section 4.1 Quiz

https://sciencesource.pearsoncanada.ca/quizzes/quiz_04_1RHUCb.htm

Section 4.2 Quiz

https://sciencesource.pearsoncanada.ca/quizzes/quiz_04_2G0jMB.htm

Section 4.3 Quiz

https://sciencesource.pearsoncanada.ca/quizzes/quiz_04_3iUc4d.htm

Matching Quiz

https://sciencesource.pearsoncanada.ca/resources/gr7_matchquiz_ch04/

Labelling Quiz

https://sciencesource.pearsoncanada.ca/resources/gr7_labelquiz_ch04/

Chapter 4 Review Quiz

http://wps.pearsoned.ca/ca_school_ontarioscience_7-8/102/26140/6691990.cw/content/index.html

Grade 7 Structures Test Study Guide

Grade 7 Structures Test Study Guide

Please review your notes and the information in the package to help you study.

Ergonomics

What is it?

·      Why is it important?

Ways to classify structures

·       Form, function, construction

Ways to classify form

·       Frame, Shell, Solid, Combination

External Forces

·       Gravity, Weather, Earthquakes, Wind, etc.

Internal Forces

·       Tension, Compression, Shear, Torsion

External Forces and Loads

·       Dynamic (moving): cars, trucks, people, wind,

·       Static (non-moving) Loads: weight of the structure, snow pack etc.

Describing Forces:

·       Magnitude

·       Direction

·       Point and Plane of Application

Designing for Safety

·      

Engineers design for a hundred year storm

·       Risk Management

o   Ignore the risk

o   Avoid the risk

o   Design for the risk

·       Use of sensors: types of sensors

GRADE 8 ENGLISH ONLY: Links to Free Verse Poetry Sites

The Best Free Verse Poems of All Time

http://www.thehypertexts.com/The%20Best%20Free%20Verse%20Poems%20of%20All%20Time.htm

Poetry 180 

http://www.loc.gov/poetry/180/p180-list.html

Designing for Forces (Notes)

Designing for Forces

Engineers have to consider all these forces when designing structures, e.g., they have to consider the load of the snow on a bridge in addition to the truck.  

Engineers design structures to withstand a hundred year storm, a large storm that occurs once in a hundred years. 

Describing Forces (Notes)

Describing Forces

To describe forces, engineers use three main things:

• The force’s:
• Magnitude (strength)
• The size of force compared to the size and weight of object
• Direction
• Where the force is coming from
• The point and plane of its application
• Point of application: the exact location where the force meets the structure
• Plane of application: the side of the structure affected by the force 

Forces That Can Act on Structures (Notes)

Forces That Can Act on Structures

• Structures constantly experience forces; they must be designed to withstand the forces they will face (Force: any push or pull)
• If the structure isn’t strong enough it may experience structural failure.
• If the structure is too strong, time and resources may have been wasted.

Internal and External Forces

• External force: acts on an object from outside the object; e.g., wind, gravity, earthquakes
• Gravity
• is a natural force of attraction
• acts on all structures all the time
• pulls structures towards Earth’s centre

• other external forces
• a person on a ladder
• pulling a drawer open
• sitting on a chair
• cars on a bridge

• Internal force: one part of a structure acting on another part of a structure; e.g.,
• tension in stretched cables on a bridge
• compression by the weight of a roof on the walls

External Forces and Loads

Every structure supports a load

• Total load: the sum of all the static and dynamic loads
• Static load: the effect of gravity on a structure (the weight of the structure itself) also called dead load
• Dynamic load: the force that moves or changes while active on the structure
• Called “dynamic” because they change their magnitude, direction, and point and plane of application.
• Wind is considered a dynamic load because its magnitude can change

E.g., a bridge: The static load is the weight of the bridge itself (dead load).

The dynamic load is the weight of the moving cars across the bridge (also called live load).

DRAW PICTURE OF TRUCK ON BRIDGE WITH LABELS HERE

Internal Forces

• Can be classified as:
• Compression – a force that squeezes or presses something together
• Tension – a force that stretches apart to expand or lengthen
• Shear – a force that pushes in opposite directions
• Torsion – a force that twists
• Bending – A force that acts to bend a component putting one side of the part in tension and the opposite side in compression

Structures: Form and Function Notes

Structures: Form and Function

Structure: something made up of parts that are together in a particular way for a specific purpose or purposes

Form: the basic shape of the structure

Function: the job that the structure does

Force: Any push or pull that can make an object change shape, speed, or direction

Ergonomic design: designs that take into account information about the human body. Ergonomic design can help people from getting hurt doing repetitive tasks and those who are physically challenged

Classification of structures

Structures can be classified by their:

Function – it may contain something (a glass), support something on top (a wall), or span a space (a bridge)

Construction – how they are built and what they are built from

Form – solid, frame and shell structures also there are combination structures

Solid Structures

Most are solid all the way through, but some may have small hollow parts, e.g., an apple or a mountain.

Frame Structures

Made of parts and fastened together; the parts are often called structural components. E.g., a bicycle, a tennis racket, cars, skeleton, umbrellas.

Shell Structures

Strong and hollow structures e.g., an igloo, a domed roof, a glass; these make good containers and require few materials. Even clothes are considered shell structures.

Combination Structures

Combination of frame, shell and solid structures. E.g., a house is made of solid pieces of wood that are arranged in frame. The boards arranged in a frame provided strength to the house. 

Form and Function Answers

Considering Form and Function 

Structure	Description of Form	Description of Function
Desk	Made from wood and metal It has a rectangular flat surface with four circular legs	Used to support books, binders and to provide a surface to write on.
Chair	Four legs, sometimes attached to the desk. Made from plastic and metal. Has a back support and a surface to sit on, has four legs	Used to support our bodies in a sitting position
Coat Rack	Made from wood, metal or plastic Its shape is a tall pole with a wider base; there are hooks at the top	Used to hang coats and other clothing, to hang bags
Pen	Made from plastic. Hollow container holds the ink in a stick-like shape.	Used to write with using hands
Bulletin Board	Piece of cork board attached to the wall with a metal frame. Large thin rectangular shape.	Used to display work, art or information
Shelves	Made from wood    The shape is a rectangular prism open on one side, there are flat wooden boards inside	Used to support books or other objects
Binder	Made from plastic, cardboard, and metal. Plastic covers the outside of rectangular cardboard.	Used to store and organize papers

Science Safety Test Outline

The test outline is as follows:

1. Identify the problems and solutions in the image

2. Know what WHMIS means and the names of its symbols

3. Know what HHPS means and the names of its symbols

Know precautions for HHPS products

4. Study the names of the science equipment in the package and their uses and safety precautions

5. Review the safety features in the lab; for example, the eye wash station, fire extinguisher, etc. and know what to do when a problem occurs in the lab.

Good Luck!

Links to WHMIS and HHPS Prezis

Here is some reference material about WHMIS and HHPS that I created for you.

WHMIS
http://prezi.com/ko5q-owcjchz/whmis/

HHPS
http://prezi.com/mmtahrfhlj1d/hhps/

Science Safety Test Tuesday September 16

 7A, 7C, 7D, 7E, will have their Science Safety Test on Tuesday September 16th.

7B will have their Science Safety Test on Wednesday September 17th.

A study guide will follow.

Science Equipment Sample Answers

Science Equipment

Equipment	Name	How is it used	Safety Procedures
	Beaker	Contain, heat, measure, pour liquids, test tubes, or powders	It’s fragile, be careful when handling
	Hot plate	Used for heating substances	Makes sure it cools completely; use gloves or tongs to handle hot beakers
	Graduated cylinder	Measuring liquids and powders	Don’t overflow, use a funnel. Be careful not to tip over
	Test tube	Testing and observing liquids and powders	Use test tube rack for support. Be careful it’s fragile.
	Funnel	Pour liquids into smaller openings	Pour slowly to avoid an overflow, support the funnel
	Beaker tongs	For picking up hot beakers	Pick up beaker between the middle and the top
	Microscope	Viewing microscopic objects	Very expensive and fragile
	Triple Beam Balance	Measuring weight	Meant for light objects
	Thermometer	Measuring temperature of substances	Very fragile
	Stirring rod	For stirring substances	Very fragile
	Erlenmeyer flask	Containing and heating liquids	Fragile, do not heat a sealed container

Science Safety Activity Sample Answers

Grade 7 Lab Safety Activity                        Name ______________

The drawing you received depicts unsafe procedures in the school laboratory. Answer the following questions based on this illustration and the safety guidelines listed in your textbook on pages xviii to xx.

1.       List 6 unsafe activities shown in the laboratory drawing

a.       Fire extinguisher is blocked by the chair

b.      Girl is smelling fumes directly from the test tube

c.       There is a broken test tube and other objects on the floor

d.      There is food on the table

e.      There is spilled liquid on the floor

f.        There is a lot of mess in the lab

2.       Explain why each activity is unsafe

a.       In case of fire, you would not be able to access the fire extinguisher quickly

b.      The fumes may be harmful to her nose, or worse-she should be wafting the fumes toward her

c.       The students may be cut by the broken glass and possibly trip over other objects

d.      Food may become contaminated with poison or bacteria which would harm the student when the food is ingested

e.      Someone can slip and fall if not cleaned up immediately

f.        Equipment can be damaged and books on table can be damaged

3.       Name 3 safety guidelines from your textbook that are not illustrated in the drawing

a.       Handle sharp objects carefully

b.      Treat all living things with respect

c.       Report safety concerns to teacher

4.       Read each statement and print T for true and F for false on the line provided

__F_____           The biology laboratory is a good setting for practical jokes

__F_____           The teacher is responsible for lab clean-up

__T_____           Spilled chemicals should be wiped up immediately

__F_____           It’s unnecessary to report minor laboratory accidents

__F_____           Performing experiments not assigned by a teacher is good creative procedure

__T_____           No chemicals or other materials should ever be tasted

__F_____           Be sure to smell materials directly from the beaker

__F_____           Only the teacher needs to know the location of the first aid kit

__F_____           Always throw broken glass into the garbage can once cleaned up

__F_____           Lab materials are inexpensive so do not be concerned if they break       

5.       What procedure would you follow in each of these situations

a)      Clothing on fire

Use the body wash station and someone inform the teacher

b)      Hot water spill on hand

Use the body wash to run cold water over burn, someone informs the teacher

c)       Particle in your eye

Use the eye wash station to rinse eyes for 15 minutes, inform the teacher

d)      Cut from broken glass

Inform the teacher, wash with soap and water, teacher provides Band-Aid 

e)      Group member not following safety procedures

Inform the teacher immediately 

f)       Beaker accidentally breaks on the floor

Inform the teacher and he/she will clean up the glass

g)      Your group is not sure of how to do an experiment

       Ask the teacher