LET'S PUT THESE POSTS IN MOTION!
Our existence on Earth is subjected to the laws of physics as we know them. Thus, motion is also governed on Earth by the laws of physics as we know them. Sir Isaac Newton discovered the laws of gravity, and has a significant contribution to our understanding of visible light, motion, and calculus.
First, let's all be reminded that an "object" in physics is anything that has a mass greater than zero. Since weight equals the object's mass multiplied by local gravity, any object has weight if gravity is greater than zero. According to these definitions and factual ideas, a human being, a person, meets the criteria of being an "object" in physics (no offense intended).
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According to Newton's first law of motion (inertia), an object will sustain its current state, speed, and line of straight movement, unless another force causes it to lose balance. Newton first law of motion is applicable to objects at rest (not moving at all; velocity = 0) and objects in uniform motion (object is moving; velocity is greater that zero and constant, no changes to the direction of movement).
Furthermore, when an object is in static balance (the object is stationary and not moving), the sum of forces in all directions is zero. This bears the meaning that all forces being applied to the object (actually influencing the object) are cancelling each other out. For example, if F1 represents one force applied to an object, and F2 represents a second force applied to the same object, then the object will be in static balance and existence if F1 = F2; and they are applied onto the objects in opposing directions.
A conclusion from Newton's first law is that an object's motion will result only if the sum of forces is greater than zero in a certain direction, and overcomes the object's ability to stay stable and resist motion. An object with complete static stability and balance does not move. In the second case according to Newton's first law of motion, we deal with an object that is moving, yet sustains its direction, speed, and dynamic balance.
Thus, while the object is in uniform motion, there is great enough a force to sustain its movement in a certain direction, yet there are no other forces great enough to cause it to change its velocity or direction. Thus, the object is presenting dynamic balance. Any force great enough that is applied to the object and causes it to either move faster (accelerate), move slower (decelerate), or move in a different direction from its original direction, will transition the object from dynamic uniform movement, to dynamic variable movement (imbalanced movement).
Let's apply this knowledge to our body and movement/motion analysis. According to Newton's first law of motion, our body will stay motionless as long as no force causes the body to lose its stability and balance. In addition, the human body will stay put, as long as no force accelerates it from zero velocity to a velocity greater than zero (resulting in movement/motion). A possible conclusion would be that in order to set a static object in motion, at least a short phase of imbalance must be created.
In summary, only forces that are actually applied to an object, have the potential of influencing its current status. Only forces greater than all opposing forces, will create movement in the direction they were applied onto the object. Forces that are actually applied onto an object, are called "applied forces". Applied forces have the potential of causing an object to move.
If the sum of all forces applied to an object is zero in all directions, the object will not move and stay stationary. An object moves less and tends to move less the greater its stability and balance are. Humans can accelerate, decelerate, and change movement direction, by applying forces in certain way, that results in the imbalance of our body. Perhaps the most prominent example of "breaking" Newton's first law of motion is the movement component of agility. The greater a person's agility, the greater their ability to change their body's 3D conformation, resulting in their ability to change to location of body parts, and change their movement direction often, and sharply.
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In the next post of this mini-series of posts dedicated to Newton's laws of motion, we will discuss Newton's second law of motion, and how it is applicable to human movement.
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