Design Technology Projects - Algebra in everyday mechanisms

Overview

Advanced Mechanisms

   - Introduction
   - Materials
   - What is a mechanism
   - Lever classes
   - How to use Scissors
   - Salad tong geometry
   - Finding a function
   - Hooke's Law
   - Visualizing vectors
   - Measuring force
   - Extreme scissors
   - Downloads

Mechanimations

Mapping

Designed Environments

Packaging

Signs, Symbols & Codes

Fixing & Fastening

Home

Salad Tongs Geometry

Input and output ranges, effort arm and load arm

Procedure: Using the Salad Tongs Geometry Worksheet each group measures the input and output ranges of motion of a pair of salad tongs, and calculates the ratio of (input range)/(output range). Does it matter whether the measurements are made using arc lengths or chord lengths? This issue can be explored either by taking measurements, and/or by plane geometry. Students then measure the effort arm and load arm and take a second ratio: (effort arm) /(load arm). How do the two ratios compare?

The image below shows the four quantities that need to be measured. The input and output ranges show how far the input (effort) and output (load) actually move when the mechanism is used. As we have seen in the previous activity, the effort arm and load arm are the distances of the input (effort) and output (load), respectively, from the fulcrum.

Effort arm, load arm, input range, output range

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