Newton's First Law of motion- law of inertia

Definition: An object stays in the same form (at rest or moving) in the same speed and direction unless acted upon by a unbalanced force.

Have you ever wondered why your body moves forward when a bus brakes and why your body tends to lean back when the bus speeds up? This is because be it an object or a living thing, we tend to "keep on doing what we are doing", which means that we tend to want to stay in the position we are in. The force of the road on the locked wheels provides the unbalanced force to change the car's state of motion, however we have no unbalanced force to change our state of motion. Thus, when the car breaks, we continue in motion, making us lean forward. In this case, seat belt is invented which would provide the unbalanced force to bring us to a state of rest from a state of motion. However, what is unbalanced forces which was used throughout the explaination?

Unbalanced forces are two forces of equal magnitude and are in opposite directions balancing each other. An example is when a book is resting on a table. The two forces involved are the table which pushes the book upwards and the gravity pull which pulls the book downwards. The book is said to be at equilibrium. There is no unbalanced forces acting on the book, enabling it to maintain its state of motion (when all the forces acting on the book are balanced, there is no unbalanced force and thus the book maintains its state of motion).

However, if a person pushes the book and made it accelerate forward, the object is said to be acted upon as there is no other force with equal magnitude and in the opposite direction to balance the unbalanced force.

Reflections: I feel that this topic which have not been taught yet, is quite easy to understand and also very interesting. I chose this topic because I am very puzzled by the fact that when a bus accelerates, my body moves backwards instead of moving forward and vice versa. As I was searching on the internet for the answer, I found this interesting topic- law of inertia. I decided to research more on it and finally found the answer to it. I will continue to research on topics which are linked to our lives as I find them very captivating and I hope you will look forward to my next post!

Sources: http://www.physicsclassroom.com/class/newtlaws/u2l1d.cfm#balanced
http://www.physicsclassroom.com/class/newtlaws/u2l1a.cfm