General Science: Physics in Daily Life

Definition: Physics is the study of matter, energy, motion, and their interactions, originating from the Greek word "physis" (nature).
The Scientific Method: Involves observation, question formulation, hypothesis development, experimentation, data collection, conclusion drawing, and theory refinement.
Standard SI Units:
- Length: meter ( $m$ )
- Mass: kilogram ( $kg$ )
- Time: second ( $s$ )
- Temperature: kelvin ( $K$ )
- Electric current: ampere ( $A$ )

Ancient Period: Philosophers like Aristotle used observation and logic to explain nature.
Scientific Revolution ( $16^{\text{th}}$ and $17^{\text{th}}$ centuries): Figures like Nicolaus Copernicus, Galileo Galilei, Johannes Kepler, and Isaac Newton introduced mathematical reasoning and experimentation.
Modern Physics ( $20^{\text{th}}$ century): Albert Einstein (Relativity) and scientists like Max Planck, Niels Bohr, Werner Heisenberg, and Erwin Schrödinger (Quantum Mechanics) expanded the field to atomic and cosmic scales.

Mechanics: The study of motion and forces, divided into kinematics (describing motion), dynamics (causes of motion), and statics (equilibrium).
Thermodynamics: Focuses on heat, temperature, and energy conversion; follows the principle that energy is transformed rather than created or destroyed.
Electromagnetism: The study of electric charges and magnetic fields; James Clerk Maxwell demonstrated that light is an electromagnetic wave.
Optics: Explores the behavior of light, including reflection (bouncing) and refraction (bending through different media).
Acoustics: Concerned with the production, transmission, and reception of sound vibrations through solids, liquids, or gases.

Relativity: Einstein’s theory that space and time are interconnected and gravity results from space-time curvature; essential for GPS accuracy.
Quantum Mechanics: Describes the behavior of matter at atomic and subatomic levels, where particles like electrons exhibit dual wave-particle properties.
Nuclear Physics: Focuses on the atomic nucleus, radioactive decay, and nuclear reactions used in medicine and energy.
Particle Physics: Investigates fundamental particles like quarks and neutrinos; notable for the discovery of the Higgs boson in $2012$ .

Refrigeration Cycle: Operates via thermodynamics through evaporation (heat absorption), compression (heating gas), condensation (releasing heat), and expansion (dropping pressure).
Microwave Ovens: Use a magnetron to produce high-frequency electromagnetic waves that vibrate water molecules to create thermal energy.
Lighting Efficiency: Incandescent bulbs convert only $5-10\%$ of energy into light, wasting the rest as heat; LED bulbs are $80\%$ more efficient and last up to $25,000$ hours.
Running Biomechanics: Modern shoes use PEBA (Polyether Block Amide) foam, which provides up to $85\%$ energy return, compared to $55-65\%$ from traditional EVA (Ethylene-Vinyl Acetate) foam.
Health and Safety: Physics principles enable diagnostic tools like X-ray, MRI, and ultrasound, as well as automotive safety features like crumple zones and airbags.