Newton ‘s Laws and Jiu Jitsu

NEWTONIAN LAWS according to excercisephysiologists.com

1)Law of Inertia Newton ‘s 1st Law states that an object continues in a state of rest or of uniform motion in a straight line unless acted upon by an external force. Inertia is Latin for idleness or laziness. The Law of Inertia can be interpreted as everything in the universe is lazy, thus requiring a force to get it on the move (which then occurs in a straight line). Once moving, more force is needed to slow it, stop it, or to speed it up or to change direction. Inertia is the body’s resistance to change in movement. It is proportional to mass, thus the mass of an object is the measure of its inertia.

Therefore, mass is the quantity of resistance to change. It should not be confused with weight. The weight of a person (or an object) is the measure of force with which the earth pulls on the body’s mass. This downward gravitational force is the body’s weight directed towards the earth’s center. Understandably so, a body’s mass and weight are directly proportional. The more mass a body has, the greater the earth’s attraction on it, the more it will weigh. Weight is a force; whereas, mass is not. It has no direction. Mass is the resistance to change (i.e., inertia).

2)Newton ’s 2nd Law (the Law of Acceleration) When a body is acted upon by a force, its resulting acceleration is proportional to the force and inversely proportional to the mass. Hence, with a constant mass, the greater the force, the greater the acceleration. And, with a constant force applied, the greater the mass, the less the acceleration. Another way of saying the same thing is: “The velocity of a moving object will remain constant unless a force acts on it.”

3)Newton’s 3rd Law (the Law of Action and Reaction) The third principle of motion can be stated as follows: If one body exerts a force on another body, the second body will exert an equal and opposite force on the first body. Hence, it is sometimes referred to as the principle of action and reaction, which can be stated: “For every force, there is an equal and opposite reaction force.

Essentially, Newton’s 3rd Law is a statement that forces always exist in pairs. For example, when we take a step forward, we press our foot against the floor. Because of the friction between the foot and the floor, we exert a backward force on the floor. The reaction force is the equal and opposite force exerted by the floor on our foot. It is this force, which acts in the forward direction, that moves us in the forward direction.

Newton ‘s Laws and Jiu Jitsu.