# Understanding Inertia

### Introduction

Force is a subtitle in Force and Motion, the second chapter in SPM form 4 physics. In force, we have 5 main subtopics: inertia, momentum, effects of force, gravity and force as a vector.

In inertia, we will discuss Newton’s First Law, situation involving inertia, mass and inertia and reducing negative effects of inertia.

In momentum, we will discuss conservation of momentum, where we will discuss 2 cases of reaction: collision and explosion. We will also discuss the applications of conservation of momentum.

In effects of force, we will discuss Newton’s 2nd Law, Newton’s 3rd Law, impulse and impulsive force and safety feature of vehicles.

In gravity, we will discuss gravitational field, free falling, lift and pulley.

In force as a vector, we will discuss addition of vectors, resolution of vectors, inclined plane and equilibrium of forces.

In this lesson, we will begin with inertia.

In inertia, we will discuss what is inertia, some situations involving inertia, mass and inertia and reducing negative effects.

### Inertia

Inertia is the property of a body that tends to maintain its state of motion.

Well, let’s see what does this mean. Let’s take the example of a driver in a car. When the car star moving, and the driver start speeding up the car, he will find that his body tends to move backward. According to the concept of inertia, before the car move, his body is in stationary state. When the car start moving forward, his body tends to maintain its state of motion, which is stationary. Well, if a car want to move forward, but your body don’t‘ want to move, the result will be your body being left behind by the car. This make the driver looks like being thrown backward when the car accelerate. This is what inertia mean. The body of the driver tends to maintain its state of motion and resist any attempt to change its state of motion.

Let’s look at another situation. When the car is moving and the driver stop the car suddenly, his body will be thrown forward. This can also be explained by the concept of inertia. When the car is moving, the driver in the car is also moving at the same speed as the car. When the car stop, according to the concept of inertia, the body of the driver will tend to maintain its state of motion, and keep on moving forward at the same speed. In other words, the car want to stop, but the body of the driver don’t want to stop, due to the effect of inertia. As a result, the body is thrown forward.

In conclusion, according to the concept of inertia, a non-moving object will tend to become not moving and resist any attempt to make it move. A moving object will keep on moving in a straight line at a constant speed and tend to resist any attempt to change its speed or direction.