Chemistry! Hooray!
Tuesday 15 December 2015
Monday 7 December 2015
Scientific Method Video
Follow the link below to find the Brainpop video we viewed in class. There are a few activities you can do as well.
https://www.brainpop.com/science/scientificinquiry/scientificmethod/
Thursday 3 December 2015
CHAPTER 5 TEST DATE
CLASSES 7A, 7C, 7D, and 7E WILL NOW HAVE THEIR TEST ON FRIDAY DECEMBER 11th 2015
CLASS 7B WILL HAVE THEIR TEST ON MONDAY DECEMEBER 14TH 2015
Additional Online Review
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!
You may ignore concepts from section 5.2 if you come across them in the chapter review.
Section 5.1
Quiz
Chapter 5 Review Quiz
Chapter 5 Matching Terms
Chapter 5 Labeling Practice
5.1 Crossword
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.
Remember, this test only covers section 5.1 in the textbook.
□ arch
□ beam
□ box beam
□ cantilever
□ centre of gravity
□ column
□ corrugated
cardboard
□ corrugated metal
□ ergonomics
□ failure
□ fatigue
□ girder
□ I-beam
□ product recall
□ stability
□ truss
□ structural
components
□ structural failure
□ structural fatigue
□ structural stress
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)
Section 5.1 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
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
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
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
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 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:
·
high
levels of paint in children’s toys
·
choking
hazards in products for children
·
overheating
batteries, poor safety features
·
cars
with faulty parts or design
Tuesday 1 December 2015
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