Week 21 - Machines Help Us Do Work

Introduction

Read pages 258 - 260 & 315 - 320
 
Mechanical Systems

Silly Machines

Rube Goldberg is a cartoonist famous for his complicated silly machines for doing simple tasks. The first is a method of sharpening a pencil, the second is a method of keeping a store window clean.



To find out more about this interesting man go to this site.

http://www.rube-goldberg.com/


These silly cartoons do illustrate one important concept of mechanical systems. Large complicated machines are always composed of several smaller machines.

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Lesson 1

Lesson 1: Introduction to Mechanical Devices


You use machines on a daily basis.

You use a machine, the can opener, to open a can of corn or peas.
If you need to fix a broken piece of furniture you might use a machine called a screw.



A baseball player or hockey player uses a machine, called a lever, every time they swing a bat or take a slap shot. A machine is any device that makes work easier by changing the size or direction of the force applied to it.
Humans and some animals use machines to meet a particular need. In this activity, you will investigate examples of mechanical devices used to meet a human need. If time permits, you will build a short multimedia presentation on these mechanical devices.

Did You Know?

The tin can was invented 130 years before the can opener. For a long time a hammer and chisel were the only ways to open cans.

Exercise 1.1: Intro to Mechanical Devices

Ancient Technology
The Great Pyramid of Giza in Egypt was built nearly 5000 years ago using blocks of limestone. The workers needed to move 2.3 million blocks each weighed more than 1 tonne. How did they do that?

 

 
Modern skyscrapers and towers defy gravity and reach hundreds of meters into the air. Instead of limestone blocks, the builders of today use steel and concrete to construct these monuments to humanity's progress. How do they do that?