Key Concepts to Know for Fundamental Principles of Physics

Fundamental principles of physics lay the groundwork for understanding how the universe operates. From Newton's laws of motion to the complexities of general relativity, these concepts explain everything from everyday actions to cosmic phenomena.

1. Newton's Laws of Motion

   • First Law: An object at rest stays at rest, and an object in motion stays in motion unless acted upon by a net external force.
   • Second Law: The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass (F=ma).
   • Third Law: For every action, there is an equal and opposite reaction, highlighting the interaction between forces.

2. Conservation of Energy

   • Energy cannot be created or destroyed; it can only be transformed from one form to another.
   • The total energy of an isolated system remains constant over time.
   • Different forms of energy include kinetic, potential, thermal, and chemical energy.

3. Conservation of Momentum

   • The total momentum of a closed system remains constant if no external forces act on it.
   • Momentum is the product of an object's mass and its velocity (p=mv).
   • Collisions can be elastic (kinetic energy conserved) or inelastic (kinetic energy not conserved).

4. Law of Universal Gravitation

   • Every mass attracts every other mass with a force that is proportional to the product of their masses and inversely proportional to the square of the distance between their centers.
   • The gravitational force is described by the equation F = G(m1*m2)/r², where G is the gravitational constant.
   • This law explains the motion of planets, moons, and other celestial bodies.

5. Laws of Thermodynamics

   • First Law: Energy cannot be created or destroyed, only transformed (conservation of energy).
   • Second Law: The total entropy of an isolated system can never decrease over time, indicating the direction of spontaneous processes.
   • Third Law: As temperature approaches absolute zero, the entropy of a perfect crystal approaches zero.

6. Electromagnetic Theory

   • Describes the behavior of electric and magnetic fields and their interactions with matter.
   • Maxwell's equations unify electricity and magnetism, showing how changing electric fields produce magnetic fields and vice versa.
   • Electromagnetic waves, including light, are produced by oscillating electric and magnetic fields.

7. Wave-Particle Duality

   • Particles, such as electrons and photons, exhibit both wave-like and particle-like properties depending on the experimental setup.
   • This duality is fundamental to understanding quantum mechanics and challenges classical physics concepts.
   • Key experiments include the double-slit experiment, which demonstrates interference patterns indicative of wave behavior.

8. Quantum Mechanics Principles

   • Describes the behavior of matter and energy at the atomic and subatomic levels.
   • Key concepts include quantization, wave functions, and the uncertainty principle, which states that certain pairs of physical properties cannot be simultaneously known with arbitrary precision.
   • Quantum entanglement illustrates the non-local connections between particles.

9. Special Relativity

   • Introduced by Einstein, it states that the laws of physics are the same for all observers in uniform motion relative to one another.
   • Time dilation and length contraction occur at speeds approaching the speed of light, leading to the conclusion that time and space are interconnected.
   • The famous equation E=mc² shows the equivalence of mass and energy.

10. General Relativity

    • Extends special relativity to include acceleration and gravity, describing gravity as the curvature of spacetime caused by mass.
    • Objects follow geodesics, or the shortest paths, in curved spacetime, which explains planetary orbits and gravitational phenomena.
    • Predictions include the bending of light around massive objects and the existence of black holes.