Introduction to Physics Why is Physics Important

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What is Physics Definition

Physics is a branch of natural science that involves the study of matter, energy, and how they relate to each other over time and through space.  This field investigates a broad range of phenomena in nature, such as understanding the structure of the atom and learning about mechanics, heat, light, radiation, sound electricity, and magnetism. 

               The study of physics is a process that starts with formulating a theoretical principle based on the observation in the natural world.  Experiments are then conducted to examine the principle and the results are used to formulate scientific laws, usually expressed in the language of mathematics. 

               The benefit to students who take a physics course is that they will learn a variety of laws and gain a better understanding of how the physical universe affects the world around us.  More importantly, the study of physics will help students develop analytical abilities and critical thinking skills that will be useful academically, and after graduation in their professional career.   

Science and the Realm of Physics

Science involves the systematic approach to studying the structure and behavior of the natural world.  Through this process, knowledge is created and organized in the form of testable explanations and predictions. 

               Physics is the study of energy, motion, space and time.  The aim of physics, which is referred to as the realm of physics, is to describe the function of the natural world around us.  A realm of physics example is forming an explanation of how an incandescent filament emits light when it becomes hot as electrons flow through it. 

Applications of Physics

There are many laws of physics that have been established.  Understanding these laws is useful to scientists as they make new discoveries and develop new technologies.  

               Knowing the principles of physics is also useful for engineers.  For example, using the system pressure value and size of a hydraulic cylinder, a fluid power engineer can determine if there is enough force available by the piston rod to lift a certain weight.  An electrical engineer performs a calculation using a known voltage value applied to an electrical circuit and the total resistance of the components used to find how much current is flowing.  The current value is compared to values listed in a table to show the wire size that is safe to carry this current.   A mechanical engineer determines the lifting capacity of an earth mover by performing calculations using the force from a cylinder and the length of a linkage.

Many of the products we use today are the result of calculations performed that are based on physics principles.    

Models, Theories, and Laws; The Role of Experimentation

Laws of nature that describe the universe around us have been developed and established as an attempt to understand them. The establishment of these laws is the result of organized and formalized collection and analysis of data through experimentation.  Based on the data, models, theories and laws are formulated.   

A model is a representation of something that is either too difficult or impossible to actually observe, such as what makes up DNA. These models help to analyze the makeup or behavior in the analysis of a scenario, to perform a mathematical calculation, or to use in a computer program when performing a simulation of the actual law being studied.   A theory is an explanation based on observations and evidence collected through experimentation.  A law is a concise set of rules or descriptions about the subject that was studied after the observation and experiments are performed and analyzed.  Once a law has been established, it is assumed to be valid until an experiment performed at a later time proves otherwise.  

The Evolution of Natural Philosophy into Modern Physics

Starting in ancient times, the study of nature came to be called “natural philosophy” that included many fields such as astronomy, chemistry, biology, mathematics, and medicine. Since that time, the accumulation of knowledge has grown to the point where it has become necessary to organize natural philosophy into separate fields.

From the time of the Resonance to the end of the 19th century, the natural science of physics was named classical physics.  Since the beginning of the 20th century, it is referred to as modern physics

Difference between Classical and Modern Physics

Classical and modern physics can be distinguished from each other by the size and speed of matter. Classical physics describes matter as it moves at speeds less than 1% of the speed of light, and objects that can be seen by a microscope.  The migration to modern physics occurred because of two revolutionary theories being added to physics in the 20th century, relativity and quantum mechanics.  Relativity deals with objects traveling faster than 1% of the speed of light.  Quantum mechanics deals with objects smaller than what can be seen by a microscope. Some of the theories established during the classical era have been brought into question or have been contradicted since the transition to modern physics. 

Review Questions

1. The study of physics starts with conducting an experiment to verify a theory. T/F 

2. The study of physics will help students in which way? 

  • Develop analytical skills
  • Develop critical thinking skills
  • Gain an understanding of the physical value
  • All of the above

3. _______ is concerned with describing the interaction of energy, matter, space and time.

4. Do physics principles apply to multiple fields? Yes/No

5. A _______ is an explanation based on observation and evidence collected through experimentation.

  • model
  • theory
  • law
  • hypothesis

6. ______________ describes matter as it moves at speeds less than 1 percent of the speed of light and objects that can be seen by a microscope.


  1. F
  2. d
  3. Physics
  4. Yes
  5. b
  6. Classical physics        
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