Lesson Notes By Weeks and Term - Junior Secondary 3

Machine motion I

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TERM – 3RD TERM

WEEK FIVE

Class: Junior Secondary School 3

Age: 14 years

Duration: 40 minutes of 5 periods each

Date:

Subject: BASIC TECHNOLOGY

Topic: MACHINE MOTION I

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

  1. Define linear motion
  2. Discuss the arrangement of lever, linkages, slides and slots to produce Linear Motion in mechanical system
  3. Describe the uses of slides and slots in mechanical system

INSTRUCTIONAL TECHNIQUES: Identification, explanation, questions and answers,

demonstration, videos from source

INSTRUCTIONAL MATERIALS: Videos, loud speaker, textbook, pictures,

INSTRUCTIONAL PROCEDURES

PERIOD 1-2

PRESENTATION

TEACHER’S ACTIVITY

STUDENT’S

ACTIVITY

STEP 1

INTRODUCTION

The teacher do a recap about linear motion in engineering.

Students pay

attention

STEP 2

EXPLANATION

Teacher explains how a lever, linkages, slides and slots will be arranged to produce Linear Motion in mechanical system

 

Students pay

attention and

participate

 

STEP 3

DEMONSTRATION

Teacher discusses the uses of slides and slots in mechanical system

Students pay

attention and

participate

STEP 4

NOTE TAKING

The teacher writes a summarized

note on the board

The students

copy the note in

their books

 

NOTE

MACHINE MOTION

Linear motion refers to the movement of an object in a straight line, where the displacement of the object is directly proportional to time. The term "linear" implies that the motion occurs along a single, straight path without any deviation. The characteristics of linear motion in engineering include:

  1. Direction: The object moves along a specific direction, maintaining a constant path.
  2. Speed: The speed of the object can be constant or vary uniformly, but the overall motion occurs in a linear fashion.

Arrangement of lever, linkages, slides and slots to produce Linear Motion in mechanical system

In a mechanical system, the arrangement of levers, linkages, slides, and slots can be ingeniously designed to produce linear motion. Here's an overview of how these components work together:

  1. Lever: Levers are rigid structures that rotate around a fixed point called a fulcrum. They are categorized into three classes based on the relative positions of the effort (applied force), load (resistance), and fulcrum.

To use a lever arrangement to bring about linear motion, first identify the lever arm and pivot point. Apply a force to the lever arm at a distance from the pivot point, causing the arm to rotate around the pivot point.

  1. Linkages: Linkages are assemblies of rigid bodies (links) connected by joints. They can transfer motion and force between different parts of a mechanical system.

 

In the case of linear motion, various types of linkages, such as the slider-crank mechanism, can be employed. This mechanism involves a sliding joint that converts rotary motion into linear motion.

  1. Slides: Slides are components that facilitate linear movement along a fixed path. They can include linear bearings, rails, and guides that allow smooth and controlled motion. A slide can bring about linear motion by providing a smooth, inclined surface for an object to slide down. The force of gravity acting on the object causes it to move down the slide in a straight line, resulting in linear motion.
  2. Slots: Slots are elongated holes or openings in a structure. When used in conjunction with pins or sliders, they allow linear motion within a limited range. Slots can be part of a mechanism where the movement is guided along a straight path.

Uses of Slides in Mechanical System

  1. Linear slides, often equipped with linear bearings or guides, allow smooth and controlled linear motion. They are employed in applications like CNC machines, 3D printers, and other precision equipment to guide moving parts along a straight path.
  2. Adjustable slides with features like lead screws or racks and pinions enable fine-tuning of linear positions.
  3. Slides are often used in conjunction with other components to convert rotational motion into linear motion. For instance, a lead screw attached to a sliding mechanism can transform rotary motion into controlled linear displacement.
  4. Linear slides are essential in modular systems where different components need to be easily assembled and disassembled.

Uses of Slots in Mechanical System

  1. Slots can be part of mechanisms that convert rotational motion into linear motion. By guiding pins along the slots, engineers can create devices that produce linear motion as part of a larger system.
  2. Slots offer flexibility in adjusting the position of components within a defined range. By altering the position of pins within the slot, users can customize the linear motion parameters, providing adaptability to various requirements.
  3. Incorporating slots in structural components allows for modular design and the attachment of various elements.
  4. Slots provide a means for constrained linear motion.

EVALUATION: 1. Define linear motion.

  1. How can a lever be arranged in order to produce linear motion?
  2. State 3 uses of slides in mechanical system
  3. Mention 3 uses of slots in mechanical system

CLASSWORK: As in evaluation

CONCLUSION: The teacher commends the students positively