Unit D Introduction
Completion requirements
Unit D: Introduction to mechanical systems.
Watch
Watch the following introduction video for Unit D. You will see five questions during the video. Think about the questions, and think about other things you would like to learn as you study mechanical systems.
Unit D Introduction: Mechanical Systems
Figure D.I.1 – A threshing flail is an ancient machine used to separate grain from plants.
People started farming about 10 000 years ago. Farming allows people to live in one place, instead of constantly moving to hunt and gather food. When humans started farming, they developed new tools to make farming work easier.
Early farmers used tools containing levers and sharp wedges. To cut down trees for farmland, early farmers made axes from stone wedges and wood levers. They made cutting tools called sickles and scythes to harvest grain. Sickles and scythes have a circular wedge blade connected to a wood lever handle. Threshing flails are tools with two connected wood levers that remove edible grains from plants.
For thousands of years, grain farming required a lot of physical effort by humans. During the Industrial Revolution in the late 1700’s, people invented complex farming machines. These machines reduced the effort involved in growing and harvesting grain. This freed up humans to do work other than farming. Over the past 200 years, farming machines have continued to improve, to the point where only one person is needed to drive a machine. In the future, robotic farming machines will likely do the majority of farm work.
Knowing about machines is important because it helps us understand how to invent new machines to make tasks easier. You will learn more about how simple machines work together in complex machines as you work through this unit on mechanical systems.
Figure D.I.2 – In the past, people used sharp farm tools called scythes and sickles to harvest grain by hand.
Figure D.I.3 – Modern combine machines cut, thresh, and separate grains.
Questions to Think About:
- How do simple machines work together in complex machine systems?
- How can we reduce the effort necessary to perform work?
- How have machines met human needs in the past, and how will new machines meet human needs in the future?
Words to Think About:
Check the word cloud below. It pictures the important words you will learn in this unit. Likely, you will know many, but check new words or any that seem fuzzy to you! Watch for these words and combinations of these words as you read. When you see them
highlighted, you can click them to learn more about their meanings. You can also visit the course glossary and read definitions for all of these words.
Unit D: Checklist and Key Ideas
Focus On: Mechanical Systems
This unit has three sections. Each section has a key idea that will help you learn more about mechanical systems. As you work through the unit, you will complete four tasks (one at the end of each section and one unit project) that will count for marks.
On the next page is a checklist of the tasks you need to complete for the unit. On the page after that are the key ideas, lesson titles, and key questions for this unit. Note that you can reach these two pages whenever you want by clicking the "Key Ideas" and "Unit Checklist" on the top corner of almost every page in the unit.
This unit has three sections. Each section has a key idea that will help you learn more about mechanical systems. As you work through the unit, you will complete four tasks (one at the end of each section and one unit project) that will count for marks.
On the next page is a checklist of the tasks you need to complete for the unit. On the page after that are the key ideas, lesson titles, and key questions for this unit. Note that you can reach these two pages whenever you want by clicking the "Key Ideas" and "Unit Checklist" on the top corner of almost every page in the unit.