Lesson Notes By Weeks and Term - Junior Secondary 2

Friction 2

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TERM – 2ND TERM

WEEK TEN

Class: Junior Secondary School 2

Age: 13 years

Duration: 40 minutes of 5 periods each

Date:

Subject: BASIC TECHNOLOGY

Topic:  FRICTION 2

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

  1. Identify ways of reducing friction
  2. Define lubrication
  3. Identify the types and Uses of friction.

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 identify and explains the ways of reducing friction.

Students pay

attention

STEP 2

EXPLANATION

Teacher explain the meaning of lubrication to the students

Students pay

attention and

participate

STEP 3

DEMONSTRATION

Teacher discusses types and uses of friction

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

FRICTION 2

Reduction of Friction

Reducing friction is often desirable in various applications to improve efficiency, reduce wear and tear, and minimize energy loss. Below are several ways to reduce friction.

1. Lubrication: Applying lubricants like oil or grease between moving surfaces reduces direct contact, minimizing friction and wear.

2. Polishing Surfaces: Smoothing and polishing surfaces can reduce microscopic irregularities, decreasing friction between the materials.

3. Using Ball Bearings or Roller Bearings: Incorporating bearings into rotating components distributes the load and reduces friction compared to direct surface-to-surface contact.

4. Adding Teflon or Graphite Coatings: Coating surfaces with materials like Teflon or graphite can create a low-friction layer, reducing resistance.

5. Designing Aerodynamic Shapes: In aerodynamics, designing streamlined shapes reduces air resistance, minimizing friction in air flows.

6. Hydrodynamic Lubrication: Using fluids, such as oil or water, to create a hydrodynamic film between surfaces can significantly reduce friction.

7. Using Rolling Elements: Employing rolling elements like wheels or cylinders can reduce friction compared to sliding motion.

Lubrication

Lubrication is the process of introducing a lubricant between surfaces in relative motion to reduce friction, wear, and heat generation. A lubricant is a substance, typically a fluid like oil or grease, that forms a film between moving surfaces, preventing direct metal-to-metal contact.

Types of Lubrication

There are various types of lubrication methods, each designed to suit specific applications and operating conditions. The main types of lubrication include:

  1. Fluid Film Lubrication: This type of lubrication occurs when a continuous film of lubricant separates moving surfaces, preventing direct contact and reducing friction. It is common in applications where there is relative motion between components.
  2. Solid Lubrication: In solid lubrication, a solid substance, often in the form of coating or embedded particles, is used to reduce friction between surfaces. Graphite and molybdenum disulfide are examples of solid lubricants.
  3. Boundary Lubrication: Boundary lubrication occurs when there is only partial separation of the contacting surfaces by a thin film of lubricant. This type of lubrication is effective under low-speed and high-pressure conditions, where the lubricant may not fully form a fluid film.

Uses of lubrication

Lubrication is essential in various industries and applications to ensure the smooth operation, longevity, and efficiency of machinery and equipment. Here are some common uses of lubrication:

  1. Lubrication is crucial in engines, transmissions, differentials, and wheel bearings to reduce friction, dissipate heat, and prevent wear.
  2. In manufacturing and industrial processes, lubrication is used in gears, bearings, chains, and other moving parts to minimize friction and maintain equipment performance.
  3. Aircraft engines, landing gear components, and various mechanisms in aerospace applications rely on lubrication to withstand high speeds, loads, and temperature variations.
  4. Turbines, generators, and other power generation equipment use lubrication to reduce friction, enhance efficiency, and prevent wear.
  5. Ship engines, propeller systems, and other marine equipment require lubrication to withstand the harsh conditions of saltwater environments.
  6. Heavy-duty machinery, such as excavators, bulldozers, and crushers, use lubrication to handle extreme loads and prevent premature wear.
  7. Bearings and chains in various applications, from household appliances to industrial machinery, benefit from lubrication to minimize friction and extend their lifespan.

EVALUATION: 1. Mention 5 ways of reducing friction

  1. What is lubrication?
  2. Mention 5 uses of lubrication
  3. Identify and describe three types of lubrication.

CLASSWORK: As in evaluation

CONCLUSION: The teacher commends the students positively