Motion, Examples, Contact Force, Force Fields and Friction for SS 1

Class: SSS 1
Term: First Term
Week: 5
Age: 15 years
Duration: 1 hour
Subject: Physics
Theme: Interaction of matter, space, and time
Curriculum Theme: Interaction of matter, space, and time
Focal competence: Reducing friction in machines and applying friction to manage real-life situations
Key competencies/values: Communication; Collaboration
Skills:

• Reducing friction in moving parts of machines
• Applying friction in reallife situations

Previous Lesson: Rectilinear Acceleration, Units, Uni
Topic: Motion
Subject Matter: Meaning and examples of motion, Meaning of contact force, Meaning of force fields, Meaning of friction

Specific Objectives

By the end of the lesson, pupils/students should be able to:

Cognitive Domain

• Define motion with examples.
• Identify the types of motion with examples.
• Distinguish between rotational motion and circular motion.
• Identify the two types of forces: (contact force and force field).
• Discuss friction and methods of reducing it.
• Evaluate the applications and disadvantages of friction in machines and other aspects of life.
• Explain how friction aids motion and how friction hinders motion.

Affective Domain

• Appreciate the importance of friction in daily activities and machines.

Psychomotor Domain

• Demonstrate how force causes motion.
• Illustrate how friction aids motion and how friction hinders motion.

Reference Materials

The following resources were used in planning this lesson:

• 2025 New Revised Senior Secondary Education Curriculum (SSEC)
• Relevant State Unified Scheme of Work
• New School Physics for Senior Secondary Schools
• The HeadTeacher Scheme of work For The New Revised Senior Secondary Education Curriculum (SSEC)

Instructional Materials

The teacher will teach this lesson with the aid of:

• Simple Pendulum
• Stone tied to a string
• Toy car to move around in circle
• Fan
• Ink to be dropped into clean water in a beaker
• Chart showing different types of motion and forces
• Whiteboard/Chalkboard and markers/chalk

Rationale for the Lesson

This lesson provides foundational knowledge in Physics by introducing students to the concept of motion, various types of forces, and the pervasive role of friction. Understanding these concepts is essential for comprehending how objects move and interact in the physical world. It also helps students appreciate the practical applications and challenges of friction in everyday life and engineering.

Prerequisite/Previous Knowledge

Students have a basic understanding of movement, push, and pull from their everyday experiences and previous science classes.

Lesson Content/Board Summary

Motion

Meaning of Motion

Motion is defined as a change in the position of an object with respect to a reference point over a period of time. An object is said to be in motion if its position changes relative to a fixed point or observer.

Examples of Motion

1. A car moving on a road.
2. A ball rolling down a slope.
3. A person walking or running.
4. A simple pendulum swinging.
5. Blades of a fan turning.
6. Ink spreading in a beaker of water.

Types of Motion

Motion can be classified into several types based on the path taken by the object:

Translational Motion

This is motion in which an object moves from one point to another without any rotation. All parts of the object move through the same distance in the same time. It can be:

1. Linear Motion: Movement in a straight line. Example: A car moving on a straight road, a stone falling vertically.
2. Curvilinear Motion: Movement along a curved path. Example: A stone thrown into the air, a car turning a corner.

Rotational Motion

This is the motion of an object spinning about its own internal axis. The axis of rotation passes through the object itself.

Example: A spinning top, the rotation of the Earth about its axis, the blades of a ceiling fan.

Circular Motion

This is the motion of an object along a circular path around an external point or axis. The object itself does not necessarily spin.

Example: A stone tied to a string and whirled in a circle, a toy car moving in a circular track, the motion of the moon around the Earth.

Oscillatory Motion

This is a repetitive to-and-fro motion of an object about a fixed equilibrium position.

Example: The swinging of a simple pendulum, a child on a swing.

Vibratory Motion

This is a rapid, repetitive to-and-fro motion, often a special case of oscillatory motion where the movement is very fast and small.

Example: A vibrating guitar string, a tuning fork, the diaphragm of a loudspeaker.

Random Motion

This is an irregular, unpredictable, and haphazard motion without any fixed path or direction.

Example: The movement of smoke particles in the air (Brownian motion), the motion of gas molecules in a container, the flight of a butterfly.

Distinction between Rotational Motion and Circular Motion

While both involve movement in a circle, they differ in the location of the axis of rotation:

1. Rotational Motion: The object spins about an axis that passes through the object itself (internal axis).
2. Circular Motion: The object revolves around an external point or axis. The object itself may not be spinning.

Force and Motion

A force is a push or a pull that can cause an object to start moving, stop moving, change its speed, or change its direction of motion. Force is the agent that causes or tends to cause motion.

Types of Forces

Forces can be broadly classified into two main types:

Contact Force

A contact force is a force that acts on an object only when there is physical contact between the interacting objects.

Examples of Contact Force

1. Frictional Force: Opposes relative motion between surfaces in contact.
2. Normal Force: The force exerted by a surface perpendicular to an object resting on it.
3. Tension Force: The force transmitted through a string, rope, cable, or wire when pulled tight.
4. Applied Force: A force applied directly to an object by a person or another object.
5. Air Resistance: The frictional force exerted by air on a moving object.
6. Muscular Force: Force exerted by muscles (e.g., pushing a cart).

Force Fields (Non-Contact Forces)

A force field, also known as a non-contact force, is a force that acts on an object without any physical contact between the interacting objects. These forces act across a distance.

Examples of Force Fields

1. Gravitational Force: The attractive force between any two objects with mass (e.g., Earth’s pull on objects).
2. Electrostatic Force: The attractive or repulsive force between electrically charged objects.
3. Magnetic Force: The attractive or repulsive force between magnets or magnetic materials.

Friction

Meaning of Friction

Friction is a force that opposes the relative motion or tendency of motion between two surfaces in contact. It always acts in a direction opposite to the motion or attempted motion.

How Friction Aids Motion

Friction is essential for many everyday activities and helps in initiating or controlling motion:

1. Walking and Running: Friction between our shoes and the ground prevents slipping.
2. Vehicle Movement: Friction between tyres and the road provides the grip necessary for vehicles to move forward and turn.
3. Braking: Friction in brake pads helps to slow down and stop vehicles.
4. Holding Objects: Friction allows us to grip and hold objects without them slipping from our hands.
5. Writing: Friction between the pen/pencil and paper allows ink/graphite to be deposited.
6. Lighting a Matchstick: Friction generates heat to ignite the match head.

How Friction Hinders Motion

While useful, friction also presents challenges:

1. Wear and Tear: Friction causes surfaces to rub against each other, leading to wear and tear of machine parts and other objects.
2. Heat Generation: Friction converts kinetic energy into heat, which can damage machinery and reduce efficiency.
3. Energy Loss: More energy is required to overcome friction, leading to reduced efficiency in machines and increased fuel consumption in vehicles.
4. Noise Production: Rubbing surfaces can produce unwanted noise.
5. Reduced Speed: Friction slows down moving objects, requiring more force to maintain speed.

Methods of Reducing Friction

Friction can be reduced to improve efficiency and reduce wear in machines:

1. Lubrication: Applying lubricants like oil or grease between moving surfaces to create a thin film that reduces direct contact.
2. Using Ball Bearings or Roller Bearings: These replace sliding friction with rolling friction, which is much lower.
3. Streamlining: Designing objects with smooth, aerodynamic shapes to reduce air or fluid resistance (a type of friction).
4. Polishing Surfaces: Making surfaces smoother reduces the interlocking of irregularities, thereby reducing friction.
5. Using Wheels: Wheels convert sliding friction into rolling friction, making it easier to move heavy objects.

Applications of Friction

Friction is intentionally used in various applications:

1. Brakes in bicycles and cars.
2. Clutches in vehicles.
3. Tyre treads for grip.
4. Matchsticks for ignition.
5. Sandpaper for smoothing surfaces.
6. Nails and screws to hold things together.

Disadvantages of Friction

The negative impacts of friction include:

1. Wear and tear of machine parts (e.g., engine components, shoe soles).
2. Loss of energy in machines due to heat generation.
3. Reduced efficiency of engines and other mechanical systems.
4. Increased fuel consumption in vehicles.
5. Production of unwanted noise.

Teaching Methods/Instructional Techniques

Discussion, Demonstration, Guided Practice, Question and Answer, Explanation, Observation, Group Work.

Instructional Procedures

Step 1: Introduction

Time: 5 minutes

Teaching Skill: Engaging/Questioning

Teacher’s Activity: The teacher greets the students and asks them what they understand by “movement” or “changing position.” The teacher then introduces the topic “Motion” and its relevance in daily life.

Pupils’ Activity: Pupils respond to the teacher’s questions and share their ideas about movement.

Learning Point: Prior knowledge activation

Step 2: Meaning and Examples of Motion

Time: 10 minutes

Teaching Skill: Explanation/Demonstration

Teacher’s Activity: The teacher explains the meaning of motion as a change in position relative to a reference point over time. The teacher provides various examples, such as a car moving, a ball rolling, and demonstrates with a simple pendulum.

Pupils’ Activity: Pupils listen, observe the demonstrations, and contribute more examples of motion from their environment.

Learning Point: Motion definition and examples

Step 3: Types of Motion and Distinction

Time: 10 minutes

Teaching Skill: Explanation/Classification

Teacher’s Activity: The teacher explains and classifies the different types of motion (translational, rotational, circular, oscillatory, vibratory, random) with examples. The teacher uses the fan and stone tied to a string to demonstrate rotational and circular motion, highlighting their distinction.

Pupils’ Activity: Pupils listen, take notes, and ask questions for clarification. They observe the demonstrations carefully.

Learning Point: Types of motion and distinctions

Step 4: Force and Types of Forces

Time: 10 minutes

Teaching Skill: Explanation/Group Discussion

Teacher’s Activity: The teacher explains how force causes motion and introduces the two main types of forces: contact force and force fields. The teacher then guides students (in their groups) to classify examples of forces into contact forces and force fields, providing examples for each.

Pupils’ Activity: Pupils participate in group discussions, classify forces, and provide examples for contact forces and force fields.

Learning Point: Force and its types

Step 5: Meaning of Friction and its Role

Time: 5 minutes

Teaching Skill: Explanation/Illustration

Teacher’s Activity: The teacher defines friction as a force that opposes motion. The teacher then illustrates how friction aids motion (e.g., walking, braking) and how it hinders motion (e.g., wear and tear, energy loss) using real-life scenarios.

Pupils’ Activity: Pupils listen, contribute examples, and discuss the dual nature of friction.

Learning Point: Friction’s meaning and effects

Step 6: Reducing Friction, Applications, and Disadvantages

Time: 5 minutes

Teaching Skill: Discussion/Application

Teacher’s Activity: The teacher leads a discussion on methods of reducing friction (lubrication, bearings, streamlining) and evaluates the applications and disadvantages of friction in machines and other aspects of life.

Pupils’ Activity: Pupils discuss methods of reducing friction and identify practical applications and disadvantages of friction.

Learning Point: Managing friction

Step 7: Evaluation/Review

Time: 5 minutes

Teaching Skill: Questioning/Assessment

Teacher’s Activity: The teacher evaluates the learning by asking the following questions:

1. Define motion and give two examples.
2. Differentiate between rotational motion and circular motion.
3. Mention two types of contact forces and two types of force fields.
4. State two ways friction aids motion and two ways it hinders motion.

Pupils’ Activity: Pupils answer orally and in writing.

Learning Point: Motion and force understanding

Step 8: Note-Taking

Time: 8 minutes

Teaching Skill: Guided Writing

Teacher’s Activity: The teacher guides pupils/students to copy the essential Board Summary notes on motion, forces, and friction into their notebooks.

Pupils’ Activity: Pupils/students copy the notes carefully into their notebooks.

Learning Point: Recording lesson content

Step 9: Conclusion

Time: 2 minutes

Teaching Skill: Summarising

Teacher’s Activity: The teacher briefly summarises the main points of the lesson, reinforcing the definitions of motion, forces, and friction, and their importance in daily life. The teacher encourages students to observe these concepts around them.

Pupils’ Activity: Pupils listen attentively and ask any final questions.

Learning Point: Lesson consolidation

Continuous Assessment/Further Study

Type: Homework

Instruction: Answer the following questions in your Physics notebook.

1. Explain five methods by which friction can be reduced in machines.
2. Describe three real-life situations where friction is beneficial and three where it is disadvantageous.
3. Research and write a short paragraph on Brownian motion as an example of random motion.

Lesson Keywords

• Motion – Change in position over time.
• Translational Motion – Movement from one point to another without rotation.
• Rotational Motion – Spinning about an internal axis.
• Circular Motion – Revolving around an external point.
• Oscillatory Motion – To-and-fro movement about an equilibrium position.
• Contact Force – Force requiring physical contact.
• Force Field – Force acting without physical contact.
• Friction – Force opposing relative motion.
• Lubrication – Using oil/grease to reduce friction.
• Streamlining – Shaping to reduce fluid resistance.

Differentiation

For students who grasp concepts quickly, encourage them to research and present on different types of friction (static, kinetic, rolling, fluid). For students needing more support, provide simplified diagrams and additional examples, focusing on defining key terms and identifying basic types of motion and forces.

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