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Video:What Are the Major Laws of Physics?

with Khalid Robinson

Physics' 5 major laws are Newton's 3 Laws of Motion, Law of Gravity, laws of thermodynamics, electrodynamics, and Einstein's Theory of Relativity. Watch this About.com video to learn more about these major physics laws and how they are observed.See Transcript

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Transcript:What Are the Major Laws of Physics?

Hey I’m Khalid with About.com. Today we are going to cover 5 major laws of physics, using tips from the About.com guide site.

Physics is the study of energy and force pertaining to matter’s movement through space and time.  To understand and study this, physicists use a series of theories and mathematic equations that have evolved over time. 

Newton’s Three Laws of Motion

The early laws of physics were developed by Sir Isaac Newton and are collectively named Newton’s Three Laws of Motion.  These laws explain the movement of matter that is roughly larger than an atom but smaller than a galaxy and moving much slower than the speed of light.  The three laws are;

  • The Law of Inertia - an object at rest will stay at rest and an object in motion will stay in motion (with the same direction and speed) unless acted on by an unbalanced force
  • Force equals Mass times Acceleration, exerting the same force on objects of different mass will result in different accelerations because of their mass variations
  • The Action-Reaction Law, for every action there is an equal and opposite reaction. 

Today, these are the cornerstone laws of classical physics.

Law of Gravity

Additionally, Newton developed his law of gravity. The law was stated as: “Every particle of matter in the universe attracts every other particle with a force that is directly proportional to the product of the masses of the particles and inversely proportional to the square of the distance between them.” While it has since been redefined, Newton’s law of gravity was a fundamental building block of physics.

Physic's Laws of Thermodynamics

Complied though the 19th century, the laws of thermodynamics explain how heat and energy systems pertain to the law of conservation of mass.  There are three laws;

  • Conservation - Energy can change forms but cannot be created or destroyed
  • Entropy- In all energy reactions, there will always be less energy available after the reaction than there is before because energy conversions aren’t perfectly efficient.
  • Absolute Zero is unobtainable

Physic's Laws of Electrodynamics

The study of electrodynamics and electromagnetic force are the foundation of today’s electrical technology. Classical electrodynamics is composes of four laws; Gauss’s law, Gauss’s law for magnetism, Faraday’s law of induction, and Ampere’s law with Maxwell’s correction. Each of which pertain to stationary or slow-moving electric charges.

Einstein's Theory of Relativity

Modern physics began when Einstein published his Theory of Relativity, which refined classical physics theory to apply to very small particles, large objects, and objects moving near the speed of light.  With the two theories that fall under this umbrella term, special relativity and general relativity, Einstein presented a number a ideas, which include the Mass-Energy Equivalence, E=mc² (energy equals mass times the speed of light in a vacuum squared)

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