Lesson Notes By Weeks and Term v4 - JHS 3
SIMPLE STRUCTURES AND MECHANISMS, ELECTRIC AND ELECTRONIC SYSTEMS
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SIMPLE STRUCTURES AND MECHANISMS, ELECTRIC AND ELECTRONIC SYSTEMS
Download the Lessonotes Mobile Ghana app for faster lesson access on Android and iPhone.
Subject: Career Technology
Class: JHS 3
Term: 2nd Term
Week: 9
Grade code: B9.4.1.1.2
Strand code: 4
Sub-strand code: 1
Content standard code: B9.3.3.1
Indicator code: B9.4.1.1.2
Theme: TECHNOLOGY
Subtheme: SIMPLE STRUCTURES AND MECHANISMS, ELECTRIC AND ELECTRONIC SYSTEMS
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Welcome, learners! Look around you. From the bicycle you ride to school, to the bottle opener used to open a soft drink, to the machine that grinds tomatoes at the market, our world is filled with clever devices that make work easier. These devices are not magic; they work because of mechanisms. A mechanism is a system of parts that work together to change force or motion. In this lesson, we will explore the common mechanisms that are the building blocks of many machines we see and use every day in Ghana. Understanding them will help you become better problem-solvers and even invent your own simple machines.
A. What is a Mechanism?
A mechanism is a device made of two or more moving parts that work together to transfer or transform force and motion to do a specific task. In simple terms, it's a 'machine helper'. The goal of most mechanisms is to make work easier.
Key Terms: Load (L): The force that you are trying to overcome or move. It is the resistance. For example, the weight of a heavy stone you want to lift. Effort (E): The force that you apply to the mechanism to overcome the load. For example, the push or pull you exert on a crowbar. Mechanical Advantage (MA): This is the most important principle. It is a measure of how much a mechanism multiplies the effort force. It tells you how much "help" the machine is giving you.
The formula for Mechanical Advantage is: MA = Load / Effort If MA > 1, the mechanism multiplies your force, making it easier to move a heavy load. You apply a small effort to move a large load. If MA = 1, the mechanism does not multiply your force but might change its direction, which can still be very useful. If **MA 1). Examples: A crowbar lifting a rock, a pair of scissors, a seesaw.