PHYSICS

• Physics
• Secondary Education

PHYSICS

FORCES

LEVEL: SHS 1

SUBJECT: PHYSICS

TOPIC: FORCES

SUB-TOPIC: TYPES OF FORCES

WHAT CAN YOU SAY ABOUT FORCES ?

What is the force that pulls objects towards the center of the Earth?

1. Gravity
2. Friction
3. Tension
4. Magnetism

LEARNING OUTCOMES

By the end of this lesson, you must be able to;

• Distinguish between types of force

• Define friction and explain the laws of friction

INTRODUCTION

Explain the following key terms; 

• push
• pull
• gravity

INTRODUCTION

• friction
•  tension
• normal force

WHAT ARE THE TYPES OF FORCES YOU LEARNED

The concept of force is crucial for understanding the physical world.

Agree: Force is fundamental in science.

Disagree: Other concepts are equally important.

Neutral: It depends on the context.

Unsure: Need more information to decide.

There are various types of forces, each with unique properties and effects.

Agree: Understanding different types of forces is essential.

Disagree: The types of forces are limited.

Neutral: It can be complex to comprehend.

Unsure: Need examples to understand better.

Calculation of forces is necessary for solving real-world problems and designing structures.

Agree: Accurate force calculations are vital for engineering.

Disagree: Other factors are more significant in design.

Neutral: It depends on the specific situation.

Unsure: Need examples of force calculations.

LAWS OF FRICTION

The laws of friction in physics describe how frictional forces behave under different conditions. Here are the main laws of friction:

1. First Law of Friction

Proportionality to Normal Force: The frictional force (both static and kinetic) is directly proportional to the normal force exerted by the surface.

Mathematically, this is expressed as:
    Ff∝Fn
    Ff​∝Fn​

where FfFf​ is the frictional force and FnFn​ is the normal force.

2. Second Law of Friction:

Independence from Surface Area: The frictional force is independent of the apparent contact area between two surfaces. This means that friction does not depend on the size of the contact area but rather on the nature of the surfaces and the normal force.

3. Third Law of Friction:

Dependence on Surface Roughness: The frictional force depends on the nature and roughness of the surfaces in contact. Rougher surfaces generally have higher friction coefficients than smoother surfaces.

4. Coulomb’s Law of Friction:

Static vs. Kinetic Friction:
    Static Friction: The maximum static frictional force (FsFs​) is usually greater than the kinetic frictional force. Static friction prevents relative motion until a threshold force is applied.
 

It is given by:

  Fs≤μsFnwhere μsμs​ is the coefficient of static friction.

 Fourth Law of Friction:

Direction of Frictional Force: The frictional force always acts in the direction opposite to the direction of relative motion (or impending motion) of the surfaces.

MENTION THE LAWS OF FRICTION

What is the force that opposes the motion of an object?

1. Friction
2. Tension
3. Drag
4. Gravity

Which type of force keeps an object at rest?

1. Kinetic friction
2. Applied force
3. Normal force
4. Static friction

What is the formula to calculate frictional force?

1. Frictional force = mass × acceleration
2. Frictional force = velocity ÷ time
3. Frictional force = coefficient of friction × normal force
4. Frictional force = weight × distance

According to Newton's first law, an object at rest will stay at rest unless acted upon by a(n) ________ force.

1. Unbalanced
2. External
3. Balanced
4. Applied

What is the force that opposes the relative motion of two surfaces in contact?

1. Tension
2. Kinetic friction
3. Normal force
4. Gravity

Friction plays a crucial role in our everyday lives.

Agree: Friction is essential for walking.

Disagree: Friction is mostly inconvenient.

Neutral: Friction has both positive and negative effects.

Confused: Is friction really that important?

The laws of friction are often misunderstood by the general public.

Agree: Misconceptions about friction are widespread.

Disagree: People generally understand the laws of friction.

Neutral: Some people understand, while others don't.

Confused: What are the laws of friction anyway?

Different types of forces have varying impacts on objects.

Agree: Gravity and friction have different effects.

Disagree: All forces have similar impacts.

Neutral: The impact of forces depends on the situation.

Confused: How do different forces impact objects differently?

Understanding the calculations on friction is important for engineering and design.

Agree: Accurate calculations are crucial for successful engineering projects.

Disagree: Basic estimations are sufficient for most cases.

Neutral: It depends on the complexity of the project.

Confused: Are the calculations on friction really that significant?

Forces can be both beneficial and detrimental in various scenarios.

Agree: Forces can both help and hinder motion.

Disagree: Forces are generally either beneficial or detrimental.

Neutral: It depends on the specific circumstances.

Confused: How can forces have both positive and negative impacts?

Static friction is stronger than kinetic friction.

Agree: Static friction prevents movement effectively.

Disagree: Kinetic friction opposes relative motion.

Neutral: Both types of friction have equal strength.

Depends: Friction strength varies based on surface.

The coefficient of friction depends on the materials in contact.

Agree: Material properties affect frictional force.

Disagree: Friction coefficient is independent of materials.

Neutral: Friction coefficient depends on surface roughness.

Complex: Friction coefficient is influenced by multiple factors.

Increasing the normal force increases the frictional force.

Agree: More force increases resistance to motion.

Disagree: Normal force and frictional force are independent.

Neutral: Normal force has no impact on friction.

Contextual: Influence of normal force varies with surface.

Lubricants reduce friction by forming a protective layer between surfaces.

Agree: Lubricants decrease direct contact and friction.

Disagree: Lubricants have little impact on friction.

Neutral: Lubricants alter the surface roughness instead.

Depends: Effect of lubricants varies with material and conditions.

Friction can be both beneficial and detrimental in different contexts.

Agree: Friction provides necessary traction and control.

Disagree: Friction always hinders motion and efficiency.

Neutral: Friction's impact depends on the specific application.

Contextual: Friction's effects vary with the situation.

PREPARED BY

BENJAMIN AKORLOR