Basic Concepts of Physics

Definition: Physics is the study of matter, energy, and the fundamental forces of nature.
Branches:
- Classical Mechanics: Motion of objects and forces.
- Thermodynamics: Heat, energy, and work.
- Electromagnetism: Electric and magnetic fields.
- Quantum Mechanics: Behavior of particles at atomic and subatomic levels.
- Relativity: Physics of high speeds and gravitational effects.

Gravitational Force: Attraction between masses; weakest force.
Electromagnetic Force: Interactions between charged particles; responsible for electricity and magnetism.
Weak Nuclear Force: Responsible for radioactive decay; affects subatomic particles.
Strong Nuclear Force: Holds atomic nuclei together; strongest force.

Newton's Laws of Motion:
1. An object at rest stays at rest; an object in motion stays in motion unless acted upon by a force.
2. Force equals mass times acceleration (F = ma).
3. For every action, there is an equal and opposite reaction.
Law of Conservation of Energy: Energy cannot be created or destroyed, only transformed.
Law of Conservation of Momentum: The total momentum of a closed system remains constant.

Work: Defined as the product of force and displacement (W = F × d).
Energy:
- Kinetic Energy (KE): Energy of motion (KE = 1/2 mv²).
- Potential Energy (PE): Stored energy due to position (PE = mgh).
Power: Rate at which work is done (P = W/t).

Zeroth Law: If two systems are in thermal equilibrium with a third system, they are in thermal equilibrium with each other.
First Law: Energy cannot be created or destroyed (ΔU = Q - W).
Second Law: Entropy of an isolated system always increases; heat flows from hot to cold.
Third Law: As temperature approaches absolute zero, the entropy of a perfect crystal approaches zero.

Wave Properties:
- Wavelength (λ), frequency (f), amplitude, and speed (v).
- Relationship: v = f × λ.
Types of Waves:
- Mechanical Waves: Require a medium (e.g., sound).
- Electromagnetic Waves: Do not require a medium (e.g., light).
Reflection and Refraction: Change in direction of waves when they bounce off surfaces or pass through different media.

Ohm's Law: V = IR (Voltage = Current × Resistance).
Circuits: Closed loop allowing current to flow; can be series or parallel.
Magnetic Fields: Created by moving charges; described by the right-hand rule.

Theory of Relativity: Deals with the fabric of space-time and the effect of gravity on time and motion.
Quantum Theory: Describes the behavior of matter and energy at atomic and subatomic levels; introduces concepts like wave-particle duality and quantization.

SI Units: Standard measurements used in physics.
- Length: meter (m)
- Mass: kilogram (kg)
- Time: second (s)
- Force: newton (N)
- Energy: joule (J)
Dimensional Analysis: Technique for checking the consistency of equations using units.

These notes encompass key concepts in physics, providing a comprehensive overview for study and review.

Physics examines matter, energy, and the fundamental forces governing the natural world.
Main branches include:
- Classical Mechanics: Studies motion and forces affecting objects.
- Thermodynamics: Focuses on heat, energy transfer, and work.
- Electromagnetism: Investigates electric and magnetic interactions.
- Quantum Mechanics: Explores particle behavior at atomic and subatomic scales.
- Relativity: Addresses high-speed motion and gravitational effects.

Gravitational Force: The weakest force, attracting masses toward each other.
Electromagnetic Force: Involves interactions among charged particles, crucial for electricity and magnetism.
Weak Nuclear Force: Governs radioactive decay, influencing subatomic particles.
Strong Nuclear Force: The strongest force, responsible for binding atomic nuclei together.

Newton's Laws of Motion:
- An object remains at rest or in uniform motion unless acted upon by a force.
- Force (F) is the product of mass (m) and acceleration (a) (F = ma).
- Every action has an equal and opposite reaction.
Law of Conservation of Energy: Energy can only be transformed, not created or destroyed.
Law of Conservation of Momentum: In a closed system, the total momentum remains constant.

Work: Calculated as the force applied multiplied by displacement (W = F × d).
Energy Types:
- Kinetic Energy (KE): Energy of moving objects, calculated as (KE = 1/2 mv²).
- Potential Energy (PE): Energy stored due to position, calculated as (PE = mgh).
Power: The rate at which work is performed (P = W/t).

Zeroth Law: If two systems are in thermal equilibrium with a third, they are mutually in equilibrium.
First Law: Energy conservation principle expressed as ΔU = Q - W, where U is internal energy, Q is heat added, and W is work done.
Second Law: Entropy of an isolated system tends to increase; heat naturally flows from hotter to cooler objects.
Third Law: As temperature approaches absolute zero, a perfect crystal's entropy approaches zero.

Wave Properties: Main characteristics include wavelength (λ), frequency (f), amplitude, and speed (v), related by v = f × λ.
Types of Waves:
- Mechanical Waves: Require a medium for propagation (e.g., sound).
- Electromagnetic Waves: Can travel through a vacuum (e.g., light).
Reflection and Refraction: Describe how waves change direction when encountering surfaces or transitioning between media.

Ohm's Law: Describes relationship among voltage (V), current (I), and resistance (R) as V = IR.
Circuits: Allow current flow in a closed loop, can be set up in series or parallel configurations.
Magnetic Fields: Produced by moving electric charges, determined by the right-hand rule.

Theory of Relativity: Examines space-time structure and gravity’s influence on time and motion.
Quantum Theory: Details behavior of matter and energy at micro levels, introducing concepts like wave-particle duality and quantization.

SI Units: Standardized metric units in physics, including:
- Length: meter (m)
- Mass: kilogram (kg)
- Time: second (s)
- Force: newton (N)
- Energy: joule (J)
Dimensional Analysis: A method for verifying equation consistency through unit checks.