Notes, summaries, assignments, exams, and problems for Physics

Light-Year Distance and Speed of Light

A light-year is the distance traveled in one year at the speed of light ($v_{\text{luz}} \approx 300,000 \text{ km/s}$).

Gravitational Accretion and Black Holes

Gravitational accretion is a phenomenon where mass accumulates due to the gravitational attraction of matter. A black hole concentration can generate a gravitational force so strong that it prevents even the speed of light from escaping—this is the point of no return (the event horizon).

The distance from the Sun to Earth is approximately 7.7 million km. At the precise moment the Sun vanished from our view, we would still see its light for several minutes. This confirms that the light speed (300,000 km/s) takes about 8 minutes to travel the distance... Continue reading "Understanding Light-Years and Cosmic Phenomena" »

Kinematics and Dynamics

Kinematics studies movement irrespective of its causes, while dynamics analyzes the causes of motion.

Types of Motion

Translational Motion

Occurs when all points of a body change position.

Rotational Motion

Occurs when a body rotates around a fixed axis; it moves but doesn't travel linearly.

Inertial Reference System

A system where the reference point (0) is at rest or moving at a constant velocity. Earth can be approximated as an inertial reference point, despite its rotation, as this motion is imperceptible to us.

Motion Concepts

Path

The trajectory of successive positions a moving point occupies in space.

Position Vector

A vector originating from the coordinate system's origin, ending at the mobile's current position.

Displacement

1. Scientist credited with the law of electromagnetic induction: Michael Faraday
2. Faraday's first discovery regarding electromagnetic induction: A changing current in one coil induces a current in another coil.
3. Factor influencing the induced EMF in a coil near a moving magnet: The speed at which the magnetic flux through the coil changes.
4. Physical quantity measuring the amount of magnetic field crossing a surface: Magnetic flux
5. Factor affecting magnetic flux through a surface: The angle between the surface and the magnetic field lines.
6. Phenomenon of electric current generation in a coil due to varying magnetic flux: Electromagnetic induction
7. Factor determining the induced EMF in a coil: The rate at which the magnetic flux through it changes.
8. Magnitude

Thermodynamics Essentials

Thermodynamics is the science that studies the work and heat exchange between a system and its environment.

First Law

This law states that the amount of energy in any system remains constant; it can only be transformed.

Systems

System

A system is an amount of material chosen for study.

Closed System

A closed system has no exchange of mass, only energy exchange.

Isolated System

An isolated system has no exchange of energy or mass.

Open System

An open system has energy and mass exchange between the environment and the system.

Surroundings

The surroundings are the region outside the system.

Boundary

The boundary is the surface separating the system from its surroundings.

Processes

A process is any change that a system experiences from... Continue reading "Thermodynamics Fundamentals: Systems, Processes, and Equilibrium" »

Oxygen Measurement Systems

Oxygen measurement systems, including electrochemical and zirconium oxide types, are crucial for determining the percentage of oxygen present in a gas concentration.

Electrochemical Oxygen Cell Operation

An electrochemical cell generates an electric potential, similar to a battery. The value of this potential is directly proportional to the oxygen concentration in the gas mixture.

Zirconia Cell Operation

The zirconia cell also generates an electric potential based on the oxygen level in the mixture, providing an accurate measurement of the oxygen percentage.

CO Analyzers for Combustion & Environmental Control

CO analyzers are essential for monitoring and controlling combustion processes and environmental emissions. Two... Continue reading "Precision Measurement: Oxygen, CO, and Concentration Analyzers" »

Defining the Universe

The Universe is the totality of space and time, all forms of matter, energy, momentum, and the physical laws and constants that govern them. However, the term universe can be used in slightly different contextual senses, referring to concepts such as the cosmos, the world, or nature.

Age, Size, and the Big Bang

Astronomical measurements indicate that the Universe has an age of $13.73 \pm 0.12$ billion years and is at least 93 billion light-years wide.¹

The event believed to have begun the Universe is called the Big Bang. At that moment, all matter and energy in the observable Universe was concentrated at a point of infinite density. Following the Big Bang, the Universe began to expand to reach its current condition, and it... Continue reading "Understanding the Universe: Origin, Expansion, and Cosmic Fate" »

Understanding Force, Motion, and Newton's Laws

Force and Motion

Every action force is able to alter the state of movement or rest of bodies, or produce in them some deformation. A vector is a directed line segment.

Elements of the force vector:

• Point of application: The point on which force is applied.
• Magnitude: The intensity of the force.
• Direction: The line on which the force vector acts.
• Sense: Indicates which of the two possible orientations of force is adopted.

Types of Forces

Weight of a body: Gravitational traction force exerted by the Earth.

Power system: A set of forces acting on a body, equivalent to a single imaginary force.

Resultant force: The force on a body that produces the same effect as the set of all the forces acting; the vector sum... Continue reading "Force, Motion, and Newton's Laws Explained" »

Quantum Physics: Foundations and Paradoxes

The atomic world began to reveal surprising and paradoxical characteristics from the viewpoint of classical or Newtonian physics.

The Wave-Particle Duality

Based on the investigations of Einstein and Planck, the wave-particle duality destroys the traditional opposition between matter and energy. Traditionally, it was felt that matter was discontinuous and particulate in nature, while energy was considered continuous and wavelike. Conversely, according to quantum physics, both matter and energy behave as particles and waves.

Planck discovered that energy is not emitted continuously but in quanta (discontinuous packets). Shortly after, Einstein identified light quanta, which he called photons. De Broglie... Continue reading "Fundamental Concepts of Quantum Mechanics and Atomic Reality" »

Basic Concepts of Thermodynamics

Thermodynamics studies the material world by selecting a portion of the universe on which attention is focused, known as a System. The remainder of the universe is considered the environment.

Classification of Thermodynamic Systems

Thermodynamic systems are categorized based on their interaction with the environment:

• Open Systems: These systems can exchange both energy (in the form of work or heat) and matter with their surroundings.
  Example: An open glass of water.
• Closed Systems: These systems can exchange energy with the surroundings but not matter.
  Example: A sealed jar of pickles.
• Isolated Systems: These systems cannot exchange matter or energy with the environment. Consequently, the total amount of energy within

Magnetic Properties

A magnetic field is the region around a magnet where its magnetic action is exerted. Within this region, ferrous materials are attracted to the magnet. Outside this region, no attraction is observed.

The magnetic field is represented by lines of force, conventionally going from the north to the south pole. Like poles repel each other, while opposite poles attract.

Magnetic flux is the number of lines of force passing through a surface within a magnetic field.

Materials that allow magnetic flux to pass through them easily are called permeable. They exhibit low resistance to this flux, a property known as reluctance. When a permeable material is placed in a uniform magnetic field, the lines of force concentrate within it, a phenomenon... Continue reading "Magnetism and Electromagnetism: Properties, Circuits, and Induction" »