Astolot Educational Centre – Alisa Miller – Grade 7 Science

Grade 7 Form and Function Unit Review Questions ANSWERS

1. Fill in the blanks using the following words [truss, arch, stable, magnitude, rebar, centre of gravity, shape, form] a) An object is STABLE if it maintains its shape and position over an extended period of time. b) The horizontal balance point of an object is very close to its CENTRE OF GRAVITY. c) A network of beams that form triangles is known as a TRUSS. d) The strength of a beam can be changed by changing its SHAPE. e) The shape and outer physical appearance of a structure is known as FORM. f) An ARCH supports a load by directing force downward along a curve. g) Reinforcing steel rods in concrete are called REBAR. h) The term MAGNITUDE refers to the size of a force.

Astolot Educational Centre – Alisa Miller – Grade 7 Science

2. a) What is the difference between external forces and internal forces? (Sec 10.4) The difference between external and internal forces is that internal forces act between parts of a structure, while external forces act on the structure from the outside. b) List the 4 internal forces forces, and give a brief description of each. Compression – pushing down on something Tension – pulling on something Torsion – twisting something Shear – ripping something 3. Decide which internal force each scenario is describing. (Sec 10.4) a) Sitting on a cushion Compression b) Ripping a piece of paper in two Shear c) Stretching an elastic band Tension d) A sweater twisted in a clothes dryer Torsion 4. Explain four factors that can cause a structure to fail. (Sec 11.6) The four factors that can cause a structure to fail are

a) Bad design – Coming up with a design without doing proper research

b) Faulty construction – Building a structure without knowing how to build a structure

c) Extraordinary loads – Putting more weight on a structure than it was meant to hold

d) Foundation failure – The part that the structure is sitting on (the part in the ground) fails, which causes the structure to fail

Astolot Educational Centre – Alisa Miller – Grade 7 Science

5. Explain four ways that a beam can be strengthened. (Sec 11.2) A beam can be strengthened in the following ways:

a) I-Beams – changing the shape of the beam so that it is shaped like an “I”.

b) Rebar – using steel reinforcing bars to strengthen concrete c) Corrugation – folding a beam by adding in ridges, grooves, or

folds. E.g. cardboard boxes, plastic and metal roofs d) Cantilever – A beam with support at only one end

6. What is the main function of market research? (Sec 12.1) After a design is made, market research is done to figure out what the public wants to buy, so that the designers can go back and change their design if necessary. 7. Why is ergonomics important in the design of products? (Sec 12.4) Ergonomics is the science of designing structures that are safe and comfortable to use. It is important for people to be buying and using safe products. 8. Classify each of the following structures as solid, frame, shell, or combination. Explain your choices. (Sec 10.3) a) a microwave b) a beaver dam Combination Frame c) a calculator d) a baseball bat Frame Solid * Other answers are possible as long as you are able to explain your choice

Astolot Educational Centre – Alisa Miller – Grade 7 Science

9. Identify the following structures as cantilever, truss, fully supported beam, or arch. (Sec 11.2, 11.4) a) Fully-Supported beam b) Cantilever

c) Truss d) Arch