# Forces – Meaning of Force | Types of Forces | Meaning of Gravitational Force JSS 1 (Basic 7) – Basic Science

**BASIC SCIENCE **

WEEK 3

SECOND TERM

JSS 1

THEME: YOU AND ENERGY

PREVIOUS LESSON – Human Reproduction – Meaning of Pregnancy, Symptoms of Pregnancy and Where to get help and Stages of Pregnancy JSS 1 (Basic 7) – Basic Science

**TOPIC – FORCE **

**LEARNING AREA**

1. Introductory Activities

2. Definition of Force

3. Types of Force

4. Calculation of Gravitational Force

5. Balanced and Unbalanced Force

6. Revision and Weekly Assessment (Test)

**PERFORMANCE OBJECTIVES **

By the end of the lesson, the students should have attained the following objectives (cognitive, affective and psychomotor) and should be able to –

1. explain the concept of force.

2. identify contact and non – contact forces.

3. differentiate between magnetic and gravitational forces.

**ENTRY BEHAVIOUR **

The students know that it takes force to move something.

**INSTRUCTIONAL MATERIALS**

The teacher will teach the lesson with the aid of:

1. Fixed door paper, spring, rubber

2. Charts showing contact and non – contact forces

3. Knife edge and slotted weights

4. Toy car, cardboard paper, rough surface.

**METHOD OF TEACHING **

Choose a suitable and appropriate methods for the lessons.

Note – Irrespective of choosing methods of teaching, always introduce an activities that will arouse pupil’s interest or lead them to the lessons.

**REFERENCE MATERIALS**

1. Scheme of Work

2. 9 – Years Basic Education Curriculum

3. Course Book

4. All Relevant Material

5. Online Information –

Friction – Meaning, Advantages and Disadvantages of Friction (JSS 1)

**CONTENT OF THE LESSON **** **

**LESSON 1 **

INTRODUCTIONIn the school and at home, we see many moving things. We move about on our legs, vehicles move on roads, trains on the rails, aeroplanes fly in the sky and ships sail on the seas.

Movement occurs when a force is applied on a thing or object.

That is, force causes things to move.

It can also prevent things from moving.

**DEFINITION OF FORCE **

A force is a pull or push on a object.

That’s, force opposed movement or causes objects to movement.

For example, car’s accelerator and break or to change direction (steering).

**TYPES OF FORCES **

1. CONTACT FORCESContact force is defined as a force which acts between two object that is in physical contact with each other.

2. NON CONTACT FORCESContact force is defined as a force which acts between two object without any physical contact with one another.

3. MAGNETIC FORCEMagnetic force is defined as an attractive force between magnetic and non magnetic objects. Or an attractive force between electrically charged particles because of their motion.

4. GRAVITATIONAL FORCESGravitational force is defined as an alternative force that tries to pull masses together or attracts any two objects with mass.

**LESSON 2 – CALCULATION OF GRAVITATIONAL FORCE**

The value of universal acceleration on the the earth’s surface is due to gravity (g) is 9.8m/s² or 10m/s²

To calculate gravitational force (Gf), GF = MG, where M is mass and gravity.

F = mg, used for calculation of gravitational force.

**Working Examples, **

Calculate the gravitational force needed to pull down an object of

1. 25kg

2. 22 kg

3. 34kg

4. 10kg at the acceleration of 10m/s²

Solution 1Given F = MG, where M = 25kg and G = 10m/s² and F = ?

Therefore,

F = 25kg x 10m/s²

= 250N, where N (Newton) is unite of Force

**BALANCED AND UNBALANCED FORCES **

Balanced forces are equal forces in opposite direction. In this case, no change in motion of an object.

While

Unbalanced forces are equal forces that cause a change in the motion of an object.

Teacher’s/Student’s – Practical Demonstration of Balanced and Unbalanced Forces

**LESSON 3 – REVISION AND WEEKLY ASSESSMENT (TEST) **

**ASSIGNMENT**

Find out –

1. The meaning of friction.

2. Advantages and disadvantages of friction.

3. Ways of reducing friction.

**PRESENTATION**

To deliver the lesson, the teacher adopts the following steps:

1. To introduce the lesson, the teacher revises the previous lesson. Based on this, he/she asks the students some questions;

2. Guides students to push and pull, squeeze, bend and stretch objects.

Students Activities – Carry out activities as directed by teacher e.g. push and pull.

3. Provides chart showing contact and non contact forces.

Student’s Activities – Identify contact and non – contact forces.

4. Guides students to calculate gravitational force using the formula GF = MG

Student’s Activities – Practise setting up balanced and unbalanced forces.

5. Guides students to set up balanced and unbalanced forces.

Student’s Activities – Practical demonstration of balanced and unbalanced forces.

**CONCLUSION**

To conclude the lesson for the week, the teacher revises the entire lesson and links it to the following week’s lesson.

**LESSON EVALUATION **

Ask students to:1. explain the concept of force.

2. name two contact and two non contact forces.

3. state the differences between magnetic and gravitational forces.

4. describe how to set up a balanced force.

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## Friction – Meaning, Uses, Advantages and Disadvantages of Friction (JSS 1)