- Newton's first law states that an object that is standing still or moving continues to stand still or move, unless there is an external force added.
- Newton's second law states that the vector sum of all of the forces that act upon an object is equal to the mass multiplied by acceleration.
- Newton's third law says that very action creates an opposite, but equal reaction.
The three laws of inertia are also known as Newton's laws of motion and are physical laws that form the basis for classical mechanics. These laws were set by the famous physicist Isaac Newton and are one of the foundations of modern physics. In their most basic form, these laws describe the relationship between an object and the forces that are exerted upon it.
There are three laws, and each deals with a different factor when trying to explain these forces. The first law tries to define force qualitatively. The second law gives it a quantitative measure, and the third law concludes that there is no single force that can be isolated. All of these laws were compiled by Newton in 1687.
The First Law
Newton's first law states that an object that is standing still continues to stand still, and an object that is moving continues to move unless an external force acts upon the object. Newton's first law basically describes how everything around us is able to move or to stand still. There is no motion unless a force is acting upon an object. Motion or lack thereof can't change if there is no force involved.
This means that if an object is going in a specific direction, it will continue to do so unless a force stops it. It will continue to do forever. These forces control everything around us. A good example of what happens when there are no forces involved are astronauts in space. Their tools and themselves are constantly floating because no force is acting upon them if they throw something that object will continue moving indefinitely until a second force acts upon it.
The Second Law
Newton's second law states that the vector sum of all of the forces that act upon an object is equal to the mass of that same object multiplied by its acceleration. This means that the acceleration of the object is related to the force, or its magnitude, to be exact. However, it is inversely connected to the mass of that object.
What this means is that if you exerted the same type of force on two objects whose mass is different, you would get completely different accelerations. Today this seems like common sense, but it was not like that until Newton created these laws. The acceleration will always be greater on the object with the smaller mass. That is just how things work, and we accept them as such today, but who knows if we would know all of this if it weren't for Isaac Newton.
The Third Law
Newton's third law deals with one body exerting force on a different body, and it states that in that case, the second body also exerts a force on the first body. This force is opposite in direction but has the same magnitude. Every action creates an opposite reaction. Both the action and reaction are forces in this context. This means that forces usually come in pairs.
For example, sitting in a chair exerts two opposite forces. Your body exerts a force that goes downward, but the chair exerts a force that goes upwards and prevents it from collapsing. Everything follows this same symmetry. Shooting a gun is also another excellent example. One force pushes the bullet forwards, while a different one pushes the gun backward. However, the gun has a bigger mass, so the effect this force has on it is less noticeable.