Index

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

INDEX

 

• Chapter One: Force

 

• Chapter Two: Light

 

• Chapter Three: Magnetism

 

• Chapter Four: Energy

 

• Optional: Astronomy

 

• Test Your Knowledge

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Forces Around Us

CHAPTER ONE

FORCES AROUND US

 

This concept helps us to understand some basic phenomena that we notice in our daily lives like a ball falling back when we kick or throw it upwards, satellites revolving around our planet and other planets too, and what keeps us on the ground so that we don’t float in the air? Let’s begin by answering a simple question, What is Force?

In simple terms Force is the basic action of pushing and pulling. When we push or pull an object, we exert a force on it, for example, if a ball is at rest we can cause it to move by pushing it, and hence we are exerting force. Tug of War would be a better example to understand it. Imagine there are 2 teams, Team A and Team B playing against each other. If Team A wants to win the match, it has to pull harder on the rope so that their pulling amount is more than that of Team B while doing this they are applying more force on the rope.

 

Pull/Push= Exerting Force

Therefore, More Pull/Push= More Force.

 

 

 

 

Interesting Fact:

~An object at rest will stay at rest until an external force is applied

~An object in motion will stay in motion until an external force is applied.

This is one of the 3 Laws of Newton about which are mentioned later in this chapter

 

When we apply a force, it can be seen sometimes like kicking a ball, pulling a rope but sometimes we can’t see like the Gravitational force that we experience when we jump or when objects like stone fall back on the ground.

 

 

FUN FACT…...

Do you ever wonder why we don’t float in the air on Earth?

It is because of the Gravitational Force of Earth which constantly pulls us back and that is the main reason for everything falling back on the ground and not floating in the air. We can’t see this force but we can feel it.

 

 

HOW TO CALCULATE FORCE???

There is a simple formula that can help us to calculate Force. Let us start with a basic concept:

 

Force is directly proportional to Acceleration.

 

{Acceleration= change in speed upon the time taken, symbol=a

Units m/s^2}

 

Explanation:

Acceleration= (change in velocity/change in time) = Δv/Δt

 

(Δ= Delta which is used to demonstrate change)

 

(velocity is the speed with the direction in which it is directed)

 

Now if Δv/Δt is a positive value and acceleration is positive, we can say that Acceleration is increasing.

 

If acceleration is increasing, we can say that there might be an increase in the velocity

An increase in velocity means there might be an external force that is causing a change in the speed.

Also, acceleration is increasing

 

Now we can say that

 

Force ∝ Acceleration----------------------------- (1)

 

Now to remove the proportionality sign, we need to add a constant, and in every situation, Mass of the object is constant and doesn’t change plus the mass of an object also affects the Force acting on the body.

 

We can use this knowledge and add it in equation (1):

 

Force= Mass*Acceleration

And hence the formula is obtained.

 

S.I. the unit of Force is Newton (symbol=N), named after Sir Issac Newton.

1N=1 kg* 1 (S.I. unit of mass is Kg)

 

Types of Forces We Witness in our Daily Lives:

 

Gravitational Force

As discussed earlier, everything falls because of the Gravitational Force acting, how to calculate the force in that situation?

 

It is simply calculated by replacing acceleration with gravitational acceleration (g) that of Earth which has a fixed value of 9.8.

 

 

EXTRA BITS…..

A Cartesian Plane helps us mark the location of a point/object on a graph properly which we then use for further calculations. The Horizontal Axis is known as the X-AXIS. The points on the left side of the X-axis are marked with a negative (-) sign to indicate the opposite direction. For example, if a ball traveled 3m to the left and 10m to the right. Now we want to find the direction of the ball after it traveled. We will use the cartesian plane

The ball traveled -3m and +10m

Add it, 10+(-3)

=7m

Therefore the ball is 7m to the right from the starting point (0m)

The vertical axis is known as the Y-axis and after 0, when the object is falling downwards, the distance is covered in a negative direction, same reason for negative distance on X-axis.

 

 

Imagine that you throw a ball from your roof, imagine this on a Cartesian Plane.

Impressum

Verlag: BookRix GmbH & Co. KG

Tag der Veröffentlichung: 04.07.2020
ISBN: 978-3-7487-4851-9

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Widmung:
I'd like to thank my mother to help me complete and compile the book. I would l would also like to thank my teacher Ms. Mou Maiti for her help.