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1.1 Forces and structures

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Technology

Grade 8

Structures

Module 2

Forces and structures

Activity 1

Forces and Structures

  • Structures sag or give way when they are not strong enough to resist the forces that are brought to bear on them. If you are sitting on a chair, the force that you exert on that chair is static . If you rock to and fro while you are on the chair, the force is in motion and we speak of dynamic force .
    Static Force
    Dynamic Force
  • We identify the following forces:

Stress

Compression

Flexure

Shearing

Assignment 1

  1. You need to support your pencil case above the surface of your desk. The only thing that you have to help do this, is an A4 sheet of paper. Fold the paper in such a manner that you create a structure strong enough to act as support.
  1. Place two space cases 250 mm apart. Use one A4 sheet of paper to create the strongest bridge possible by means of folding to span the gap between the space cases. Test the various bridges with a variety of weights to determine which is the strongest.

LO 1.3

Assessment

Learning Outcomes(LOs)
LO 1
TECHNOLOGICAL PROCESSES AND SKILLS The learner will be able to apply technological processes and skills ethically and responsibly using appropriate information and communication technology.
This is demonstrated when the learner:
investigates:1.1 investigates the background context, the nature of the need, the environmental situation, and the people concerned when given a problem, need or opportunity set in a nationally relevant context;
1.3 develops and performs practical tests in the technological areas (Structures, Processing, and Systems and Control);
1.4 uses appropriate technologies and methods to:
  • collect relevant data from different sources and resources;
  • extract relevant data;
  • make meaningful summaries;use information to justify and support decisions and ideas;
designs:1.5 writes or communicates a short and clear statement or a design brief in response to a given identified situation for the development of a product or system;
1.6 lists product and design specifications and constraints for a solution to an identified or given problem, need or opportunity based on most of the design key words listed below:
    • people: age target market;
  • purpose: function;
  • appearance: colour, shape;
  • environment: where will product be used;
  • safety: for users;
  • cost: cost of materials;
1.7 generates several alternative solutions and writes notes, ideas that show some links to the design brief and specifications;
makes:1.9 develops a plan for making that outlines all of the following:
  • resources needed;
  • sketches showing the necessary dimensions or quantities;
  • all steps necessary to making the product;

Memorandum

ACTIVITY 1

  • Encourage the learners to illustrate the four types of force by means of additional examples.

Assignment 1

  1. Let the learners offer other ideas and discuss each idea (e.g. will a rectangular 'pillar' be stronger or weaker? Will a slender double-walled pillar (with the paper overlapping) be stronger than a more stocky pillar with single-layer walls?)
  2. Let the learners decide which factors determine strength: e.g. more shallow folds or fewer deeper folds, the type of paper, etc.
  • Allow sufficient time for learners to name examples from their daily environment. The class could discuss the examples and suggest improvements.
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Source:  OpenStax, Technology grade 8. OpenStax CNX. Sep 13, 2009 Download for free at http://cnx.org/content/col11052/1.1
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