Laws of Physics
Newton’s first law states that every object will remain at rest or in uniform motion in a straight line unless compelled to change its state by the action of an external force. This is normally taken as the definition of inertia. The key point here is that if there is no net force acting on an object (if all the external forces cancel each other out) then the object will maintain a constant velocity. If that velocity is zero, then the object remains at rest. If an external force is applied, the velocity will change because of the force.The second law explains how the velocity of an object changes when it is subjected to an external force. The law defines a force to be equal to change in momentum (mass x’s velocity) per change in time. Newton also developed the calculus of mathematics, and the “changes” expressed in the second law are most accurately defined in differential forms. (Calculus can also be used to determine the velocity and location variations experienced by an object subjected to an external force.) For an object with a constant mass m, the second law states that the force F is the product of an object’s mass and its acceleration a:
The third law states that for every action (force) in nature there is an equal and opposite reaction. In other words, if object A exerts a force on object B, then object B also exerts an equal force on object A. Notice that the forces are exerted on different objects.
So, how does Newton’s Laws of Motion revealed in a baseball swing?
Newton’s First Law of Motion
An object at rest tends to stay at rest and an object in motion tends to stay in motion with the same speed and in the same direction unless acted upon by an unbalanced force. The initiation of a batters swing begins with the hips, the biggest and strongest muscles in the body which include the legs and torso. The bat is at rest until the force of the hips, legs and torso are applied at heel drop.
Hence…the hips lead the hands!
Newton’s Second Law of Motion
The acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object.
In terms of an equation, the net force is equated to the product of the mass times the acceleration.
Newton’s Third Law
A force is a push or a pull upon an object which results from its interaction with another object. Forces result from interactions! According to Newton, whenever objects A and B interact with each other, they exert forces upon each other. Hit the ball square. When you sit in your chair, your body exerts a downward force on the chair and the chair exerts an upward force on your body. There are two forces resulting from this interaction – a force on the chair and a force on your body. These two forces are called action and reaction forces and are the subject of Newton’s third law of motion. Formally stated, Newton’s third law is:
“For every action, there is an equal and opposite reaction.”
The statement means that in every interaction, there is a pair of forces acting on the two interacting objects. The size of the forces on the first object equals the size of the force on the second object. The direction of the force on the first object is opposite to the direction of the force on the second object. Forces always come in pairs – equal and opposite action-reaction force pairs.
Rotational mechanics teach hitters to hit the ball level to the path it is on, equal and opposite to the pitched ball. The hips are working equal and opposite, the shoulders are working equal and opposite and the elbows are as well. Front hip back, back hip forward – front shoulder up, back shoulder down – front elbow up, back elbow down. It’s all connected to each other and the results are rotational mechanics!