Key Concepts in Physics

Fundamental Forces
- Gravitational Force: Attracts masses.
- Electromagnetic Force: Acts between charged particles.
- Strong Nuclear Force: Holds protons and neutrons in the atomic nucleus.
- Weak Nuclear Force: Responsible for radioactive decay.
Newton’s Laws of Motion
- First Law: An object at rest stays at rest; an object in motion remains in motion unless acted on by an external force.
- Second Law: F = ma (Force equals mass times acceleration).
- Third Law: For every action, there is an equal and opposite reaction.
Energy Principles
- Kinetic Energy: Energy of motion (KE = 1/2 mv²).
- Potential Energy: Energy stored due to position (PE = mgh).
- Conservation of Energy: Energy cannot be created or destroyed, only transformed.
Thermodynamics
- Zeroth Law: If two systems are in thermal equilibrium with a third system, they are in equilibrium with each other.
- First Law: Energy conservation in thermodynamic processes (ΔU = Q - W).
- Second Law: Entropy of an isolated system always increases; heat cannot spontaneously flow from cold to hot.
- Third Law: As temperature approaches absolute zero, the entropy of a perfect crystal approaches zero.
Waves and Oscillations
- Wave Properties: Wavelength, frequency, amplitude, speed.
- Types of Waves:
  - Mechanical: Requires a medium (e.g., sound waves).
  - Electromagnetic: Does not require a medium (e.g., light waves).
- Superposition Principle: When two waves overlap, the resulting wave is the sum of the two.
Electricity and Magnetism
- Ohm’s Law: V = IR (Voltage = Current x Resistance).
- Circuit Components: Resistors, capacitors, inductors.
- Faraday's Law: A changing magnetic field induces an electromotive force (EMF).
- Ampère's Law: Magnetic field around a current-carrying conductor.
Modern Physics
- Theory of Relativity:
  - Special Relativity: Time and space are interwoven; speed of light is constant in a vacuum.
  - General Relativity: Gravity is a curvature of spacetime.
- Quantum Mechanics:
  - Wave-particle duality: Particles exhibit properties of both waves and particles.
  - Heisenberg Uncertainty Principle: Cannot simultaneously know both the position and momentum of a particle.
Applications of Physics
- Engineering: Structural, mechanical, electrical, aerospace.
- Medicine: Imaging techniques like MRI and ultrasound.
- Environmental Science: Understanding climate change and renewable energy sources.

Units of Measurement

Length: Meter (m)
Mass: Kilogram (kg)
Time: Second (s)
Force: Newton (N = kg·m/s²)
Energy: Joule (J = N·m)

Important Constants

Speed of Light (c): 299,792,458 m/s
Gravitational Constant (G): 6.674 × 10⁻¹¹ m³/kg·s²
Planck's Constant (h): 6.626 × 10⁻³⁴ J·s

This structure provides a clear and concise overview of fundamental topics in physics, facilitating easier study and review.

Fundamental Forces

Gravitational Force: Attracts objects with mass. Always attractive, weakens with distance.
Electromagnetic Force: Acts between electrically charged particles. Attractive or repulsive depending on charges, weakens with distance.
Strong Nuclear Force: Holds protons and neutrons together in an atomic nucleus, strongest force, acts over very short distances.
Weak Nuclear Force: Responsible for radioactive decay, weaker than strong nuclear force, acts over short distances.

Newton’s Laws of Motion

First Law (Inertia): An object at rest remains at rest, and an object in motion remains in motion with constant velocity, unless acted upon by a net force.
Second Law: Force is equal to mass times acceleration (F=ma). A larger force results in greater acceleration, and a greater mass requires a larger force for the same acceleration.
Third Law: For every action, there is an equal and opposite reaction. When you push a wall, the wall pushes back on you with equal force.

Energy Principles

Kinetic Energy (KE): Energy of motion, determined by the object’s mass and velocity.
Potential Energy (PE): Stored energy due to an object’s position or configuration, includes gravitational potential energy (determined by height) and elastic potential energy (determined by stretching or compressing a spring).
Conservation of Energy: Energy cannot be created or destroyed, only transformed from one form to another.

Thermodynamics

Zeroth Law: Two systems in thermal equilibrium with a third system are in thermal equilibrium with each other. Objects at the same temperature are in thermal equilibrium.
First Law: Energy is conserved in thermodynamic processes. The change in internal energy (ΔU) of a system is equal to the heat (Q) added to the system minus the work (W) done by the system.
Second Law: Entropy (a measure of disorder) of an isolated system always increases over time. This means that heat flows spontaneously from hot to cold, never the other way around.
Third Law: As the temperature of a system approaches absolute zero (-273.15 °C or 0 Kelvin), the entropy of the system approaches a minimum value.

Waves and Oscillations

Wave Properties:
- Wavelength (λ): Distance between two successive crests or troughs.
- Frequency (f): Number of waves passing a point per second.
- Amplitude (A): Maximum displacement from the equilibrium position.
- Speed (v): How fast the wave travels, related to wavelength and frequency by the equation v = fλ.
Types of Waves:
- Mechanical: Requires a medium to travel (like sound waves).
- Electromagnetic: Does not require a medium (like light waves).
Superposition Principle: When two or more waves overlap, the resulting wave is the sum of the individual waves at each point in space.

Electricity and Magnetism

Ohm’s Law: Voltage (V) across a conductor is directly proportional to the current (I) through it, with resistance (R) being the constant of proportionality.
Circuit Components:
- Resistors: Resist the flow of current.
- Capacitors: Store electrical energy in an electric field between two conductive plates.
- Inductors: Resist changes in current due to magnetic fields.
Faraday’s Law: A changing magnetic field induces an electromotive force (EMF), which can drive a current in a conductor.
Ampère’s Law: A current-carrying conductor creates a magnetic field around it, and the strength and direction of the field are determined by the magnitude and direction of the current.

Modern Physics

Theory of Relativity:
- Special Relativity: Time and space are interconnected and relative to the observer's motion. The speed of light in a vacuum is constant for all observers.
- General Relativity: Gravity is a curvature of spacetime caused by the presence of mass or energy.
Quantum Mechanics:
- Wave-particle duality: Particles exhibit properties of both waves and particles, such as light behaving like both a wave and a stream of photons.
- Heisenberg Uncertainty Principle: It is impossible to simultaneously know both the position and momentum of a particle with perfect accuracy.