Movement

Movement, or motion, is the state of changing something's position or changing where something is. A bird that is flying is moving. So is a person who is walking. This is, because they change where they are. They "move" from one place to another. There are many forms of science and mathematics that are related to movement.

Because of the work of scientists including Galilei and Newton, we know that position is relative. This means that an object's position depends on where it exists in relation to other objects. For example, a ball can be  away from a box,  from a chair and away from a table. Here, the box, chair and the table helped to define the position of the ball. They acted as the reference points for the observation of the ball. By telling someone how far the ball was from other objects, they were told its relative position.

The motion of an object is also relative. It depends on how its position changes in relation to other objects. For example:

A person is sitting inside a train (Train A). The train has not started moving yet. When that person looks out the window, they see another train (Train B) . Both trains are facing the same direction. If Train B moves backwards, it appears to the person on Train A that they are moving toward Train B. If a reference point it added this can be changed. If the person can also see a pole next to the trains they will see that train A did not move and train B moved backwards.

From this, it is shown that what the movement is can not be known without a frame of reference. In this example the pole is the frame of reference.

The study of motion without considering its cause is called kinematics. Kinematics deals with terms like speed, velocity, and acceleration. Dynamics is the branch of physics that focuses on the causes and effects of motion. It deals with force, inertia, work, energy and momentum.

 Animal movement 
The movement of animals is controlled by the nervous system, especially the brain and spinal cord.

The muscles that control the eye are driven by the optic tectum in the midbrain. All the voluntary muscles in the body are controlled by motor neurons in the spinal cord and hindbrain. Spinal motor neurons are controlled by neural circuits of the spinal cord, and by inputs from the brain. The spinal circuits do many reflex responses, and also do rhythmic movements such as walking or swimming. The descending connections from the brain give more sophisticated control.Kandel, Eric R; Schwartz, James Harris & Jessell, Thomas M. 2000. Principles of neural science. New York: McGraw-Hill.  []

The brain has several areas that project directly to the spinal cord. At the highest level is the primary motor cortex. This is a strip of tissue at the back of the frontal lobe. This tissue sends a massive projection directly to the spinal cord, through the pyramidal tract. This allows for precise voluntary control of the fine details of movements. There are other brain areas which affect movement. Among the most important secondary areas are the premotor cortex, basal ganglia, and cerebellum.

+ Areas of the brain used un the control of movement Area Location Function Ventral horn Spinal cord  Contains motor neurons that directly activate muscles Oculomotor nuclei Midbrain  Contains motor neurons that directly activate the eye muscles Cerebellum Hindbrain  Calibrates precision and timing of movements Basal ganglia Forebrain  Action selection on the basis of motivation Motor cortex Frontal lobe  Direct cortical activation of spinal motor circuits Premotor cortex Frontal lobe  Groups elementary movements into coordinated patterns Supplementary motor area Frontal lobe  Sequences movements into temporal patterns Prefrontal cortex Frontal lobe  Planning and other executive functions

In addition, the brain and spinal cord controls the autonomic nervous system. this system works by secreting hormones and by modulating the "smooth" muscles of the gut. The autonomic nervous system affects heart rate, digestion, respiration rate, salivation, perspiration, urination, sexual arousal and several other processes. Most of its functions are not under direct voluntary control. Several of them, such as respiration, can be controlled directly as well.

 Related pages 
 Energy
 Gravity
 Kinetics
 Navigation
 Kinematics
 Atomic orbital
 Wave function
 Transportation
 Molecular orbital
 Brownian motion
 General relativity
 Root mean square
 Classical mechanics
 Quantum mechanics
 Schrödinger equation
 Newton's laws of motion
 Kepler's laws of planetary motion
 International System of Units (SI Units)

 References 

Category:Mechanics
Category:Motion (physics)
Category:Physical phenomena