Force and Laws of Motion

Have you ever wonder what was the cause which makes an object to move, the cause which change its speed or the cause which stops an moving object. If you hadn’t then congratulations you are the one of the crores of people in the world. If you had you were among the few people. One such person who had such curiosity in his mind is Sir Issac Newton. He worked hard to get the answers and finally succeed to get. He wrote a book named “Philosophiae Naturalis Principia” in which he wrote his philosophies. And from it the world came to know about “force”.

“Force is the cause which makes an object to move or tend to move, to stop or tend to stop. It is the cause which changes or tend to change the direction of motion of the body”.

For example when you kick a football it moves to some distant and then stops the cause which makes the football to move is the force applied by you on football

First Law Of Motion:

All objects in the universe resist the change in its state of motion or rest. They always tend to maintain their state of rest or motion and this tendency of an object is known as inertia. Inertia of an object can be measure by its mass. The first law of motion deals with inertia and thus also known as law of inertia. First law of motion states that:

“An object remains in a state of rest or of motion until unless an external force is applied on it”

Second Law Of Motion:

In first law of motion we were introduced by a new physical quantity called as “force”. We were aware about the force but we don’t how to calculate its magnitude. Second law of motion gives us the magnitude of force required to change the state of rest or motion of an object. It states that:

“The rate of change of momentum of an object is directly proportional to the applied unbalanced force in the direction of force”


In order to understand momentum let us recount some everyday’s life observation. A truck at rest does not require any attention when parked along a roadside but if the same truck starts moving even at a slow speed it might kill a person, taking another scenario take a bullet and throw it against a wall it will create some impact on the wall but if the same bullet is shooted by a rifle the impact will be higher and might create a hole in the wall. From the above observation we can conclude that their should be a physical quantity that shows us the combine effect of mass and velocity. Sir Issac Newton introduced that physical quantity and named it as”momentum”.

Momentum of an object is the product of of its mass and velocity and in has the same direction as that of the velocity

Third Law Of Motion:

Third law of motion is the simplest among all and applies at many places. It states that:”To every action has an equal and opposite reaction and they acts on two different bodies

which means that if you apply force on an object then you also get a reaction by the object which is equal in magnitude of the applied force but opposite in direction.

Law Of Conservation Of Momentum:

This law states that the Sum of momentum of two object before collision is equal to the sum of momentum after the collision when their is no unbalanced force acting on them.