Basic Science and Technology - Junior Secondary 3 - Simple machine

Simple machine

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TERM: 3RD TERM

WEEK: 7

CLASS: Junior Secondary School 3

AGE: 14 years

DURATION: 40 minutes each for 2 periods

DATE:

SUBJECT: Basic Science

TOPIC: Simple machine

SPECIFIC OBJECTIVES: At the end of the lesson, the learners should be able to

  1. ) Define simple machine
  2. ) Mention and explain some terms used in simple machines
  3. ) List and explain the six types of simple machines
  4. ) Outline the uses of simple machines

INSTRUCTIONAL TECHNIQUES: Identification, explanation, questions and answers, demonstration, story-telling, videos from source

INSTRUCTIONAL MATERIALS: Recommended Basic Science textbooks for Junior Secondary School 3

INSTRUCTIONAL PROCEDURES: PERIOD 1-2:

PRESENTATION

TEACHER’S ACTIVITY

PUPIL’S ACTIVITY

STEP 1

Review

The teacher revises the previous lesson.

Learners pay attention

STEP 2

Introduction

He defines simple machine. He further mentions and explains some terms used in simple machines

Learners pay attention and participate

STEP 3

Explanation

He lists and explains the six types of simples machines and states uses of simple machines

Learners pay attention and participate

STEP 4

NOTE TAKING

The teacher writes a short note on the board for the learners to copy

The learners copy the note from the board

 

NOTE

SIMPLE MACHINES
A simple machine is a mechanical device that changes the direction or magnitude of a force. It is a basic device that makes work easier by allowing humans to apply less force over a greater distance or use the force more efficiently. Simple machines have few or no moving parts and work by applying mechanical advantage to reduce effort.

 

Some Terms Used in Simple Machines

  • Effort: The force applied to a simple machine to move or lift an object. It is the input force.
  • Load: The object or resistance that is being moved or lifted by the machine. It is the output force.
  • Fulcrum: The pivot point or support around which a lever rotates.
  • Mechanical Advantage (MA): The factor by which a simple machine multiplies the input force. It is calculated by dividing the output force (load) by the input force (effort).
  • Input Distance: The distance over which the effort is applied.
  • Output Distance: The distance over which the load is moved.
  • Force: A push or pull that can cause an object to move or change direction.

 

Types of Simple Machines

  1. Lever:
    • A rigid bar or beam that rotates around a fixed point called the fulcrum. Levers are classified into three types based on the position of the effort, fulcrum, and load.
      • First-class lever (e.g., seesaw): The fulcrum is between the effort and the load.
      • Second-class lever (e.g., wheelbarrow): The load is between the effort and the fulcrum.
      • Third-class lever (e.g., fishing rod): The effort is between the load and the fulcrum.
  1. Pulley:
    • A wheel with a rope or chain wrapped around it. It is used to lift or lower heavy objects by changing the direction of the applied force. There are fixed pulleys, movable pulleys, and compound pulleys (combining fixed and movable pulleys).
  2. Inclined Plane:
    • A flat surface set at an angle to the horizontal, which allows a heavy object to be moved with less force by increasing the distance over which the force is applied. It is commonly used in ramps or slides.
  3. Wedge:
    • A double inclined plane that is used to split, cut, or separate objects. The edge of a wedge is forced into the material to separate it (e.g., an axe, knife).
  4. Screw:
    • A long, spiraled inclined plane wrapped around a shaft. It converts rotational force (torque) into linear force, making it useful for fastening objects or lifting materials (e.g., screws, car jacks).
  5. Wheel and Axle:
    • A larger wheel connected to a smaller axle. When the wheel is turned, it rotates the axle and moves objects with less effort. It is commonly used in vehicles (e.g., car wheels) and other rotating machinery.

 

Uses of Simple Machines

  • Levers: Used in tools such as crowbars, scissors, and see-saws to lift or move heavy loads with less effort.
  • Pulleys: Used in cranes, elevators, and curtains to lift or move heavy objects with minimal force by changing the direction of the force.
  • Inclined Planes: Used in ramps, loading docks, and slides to move heavy objects up or down more easily by increasing the distance.
  • Wedges: Used in cutting, splitting, or shaping materials (e.g., knives, axes, chisels).
  • Screws: Used in fastening materials together (e.g., screws, bolts) and in devices like bottle caps or clamps.
  • Wheel and Axle: Used in transportation (e.g., bicycles, cars, wagons) and machinery for easier movement or rotation

 

EVALUATION:

  1. What is a simple machine, and how does it make work easier?
  2. Explain the difference between the three types of levers, providing examples for each.
  3. How does a pulley system reduce the amount of force required to lift an object?
  4. Describe how an inclined plane works and provide two examples of where it is used.
  5. What are the advantages of using a wheel and axle system in everyday machines, and where is it commonly applied?

CLASSWORK: As in evaluation

CONCLUSION: The teacher marks their books and commends them positively