There was an intelligent guy in England named Issac Newton. He was very much interested in working on physics and calculus. During his work, he came across three basic laws ,which scientists now called Three Laws of Motion .
3 Laws are explained as below:
1) First Law of Newton :
Every object which is in a state of motion tends to remain in motion unless an external force is applied on it.Similarly if an object is in static position that is if it is not moving, it will not move unless some external force is not applied on it.In short, things are lazy. If they are moving,they will like to keep moving,similarly of they are resting, they will like to rest .You need to apply an external force to bring a change in their position. This is also called law of inertia.
b) Newton’s 2nd Law:
The second law states that if we apply the same force on two objects of different mass,we will get different accelerations (changes in motion).The effect (acceleration) on the object ;which has a smaller mass; will be more noticeable. The effect of a 10 newton force on a tennis ball would be much greater as compared to the same force acting on a baseball. The difference in effect (acceleration) is entirely due to the difference in the masses of the objects.
c) Newton’s 3rd Law of Motion:
It sates that for every action there is an equal and opposite reaction. It means that there are always pair of forces acting on two interacting objects or bodies. The direction of the force on the 1st object is opposite to the direction of the force on the 2nd object. It short, forces always come in pairs. Consider the flying of birds,it‘s an example of birds. As we know a bird flies by using its wings.The wings of a bird push the air downwards, the air works in opposite direction and it pushes the bird upwards. For every action, there is an equal & opposite (in direction) reaction. So in case of flying, action-reaction force pairs help birds to fly.