Newton’s Three Laws of Motion


Laura Zittlow, Reporter

Sir Isacc Newton: the man known for a falling apple and three laws of motion among other things. But is that story true? Indeed it is. For Newton told one of his first biographers (William Stukeley) the story, only the apple didn’t hit him in the head, it had fallen nearby. That story is an important one in that it tells of how Newton “discovered” gravity however it doesn’t partan much to this article rather it is just a bit of history. Newton’s three laws of motion are quite important when it comes to physics.

Newton’s first law is often referred to as the law of inertia which states that “a body in motion stays in motion (the body is to have constant velocity for this) and a body in rest stays at rest until a force acts upon it.”  This law is occasionally viewed as a special case of  Newton’s second law by experts, but you don’t have to worry about that. His first law is said to give meaning to the word “mass-inertia” which isn’t a recognized word. Also, the main concept of the first law is momentum as stated by Peter Ojo who is a Theoretical Physicist.

Newton’s second law of motion definition is the most awarded in that it doesn’t have a nice summary. His actual law can be stated as “the acceleration of an object is produced by a net force that is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the object’s mass”  ( Meaning acceleration is inversely proportional to an object’s mass and directly proportional to its net force. However, there is a lovely equation that can summarize it is a=F/m  where a stands for the object’s acceleration,  F stands for the said object’s net force, and m stands for the said object’s mass. The main concept of this law is that one can determine an object’s acceleration if you know the net force acting on it and its mass.

Newton’s third law is probably the most common one from a teenager’s perspective because it is easy to remember and has the fewest words. However, just because it has the fewest words doesn’t mean that it isn’t less important than the others. His third law states that “for every action, there is an equal and opposite reaction.” It is said that this law is “one of the fundamental symmetry principles of the universe,” (hyperphysics). This law tells us that forces always act in pairs.


Sources used:


Khan Academy