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

Pressure and Fluids

What is Pressure?

Sometimes the effect of force also depends on the size of the surface on which it operates. The pressure takes into account two variables: the strength and the surface. Pressure occurs when a force acts on a unit area.

Pressure is defined as the force acting on a unit area (p = F / S). The SI unit is the newton per square meter (N/m²), which is called the pascal and whose symbol is Pa (1 Pa = 1N / 1 m²). Pressure is a scalar because it acts with an equal numerical value in all directions.

What are Fluids?

The term fluid includes both liquids and gases, and their properties are:

1. They do not have their own shape.
2. They take the form of the container that contains them.

This is because the particles that make up the... Continue reading "Understanding Fluid Pressure and Hydrostatics" »

The Vastness of Space: Galaxies, Stars, and Dark Matter

The universe is a vacuum containing billions of galaxies. In turn, each galaxy contains billions of stars, planets, and nebulae. In addition to visible objects, there is matter we cannot see: the so-called dark matter. Astronomers currently estimate that stars and planets occupy only 10% of the universe, while 90% is composed of dark matter.

Elemental Composition of the Cosmos

The universe is primarily made up of light elements:

• 75% Hydrogen
• 20% Helium
• 5% Other elements

This composition was determined by comparing the spectrum of white light with the spectrum of sunlight.

Defining a Galaxy

A galaxy is a massive cluster of stars, planets, gas, and dust. It typically has a supermassive black hole... Continue reading "Secrets of the Cosmos: Universe Composition and Formation" »

1. Strength and Equilibrium

The existing state of motion, or a body at rest, is defined by the forces acting upon it, which may deform or alter the state of that body.

2. Special Forces: Weight

The weight of a body on Earth is defined as the gravitational force of attraction.

3. Composition of Forces

The resultant force affecting a body is the vector sum of all individual forces acting upon it.

4. Decomposition of Forces

Sometimes, a force is resolved into two components. This operation, known as decomposition, results in the same impact on the body as the original force.

5. Equilibrium of Forces

A body is in equilibrium when the sum of two or more forces acting upon it is null, meaning the resultant force is zero.

6. Newton's Laws and Dynamics

Dynamics... Continue reading "Understanding Physics Dynamics: Newton's Laws and Force Principles" »

Types of Support and Channels

Wireless support's atmosphere is leading to it being transmitted through electromagnetic waves and sound. Wired support uses some sort of cable, such as coaxial cable or fiber optics.

Channels

Channels are real-time media communication that allows the same instant. Time media are those media differed in the signal sent by the sender is stored in any information recording system, such as magnetic tapes, CDs, and DVDs.

Codes

Communication codes are legion: the languages of mankind, color codes, writing, and language.

Parameters

• Amplitude: The maximum variation of the signal about the value zero.
• Period: The time lag between two consecutive steps by maximum wave value.
• Frequency: The number of oscillations that occur during

Swing Circuits and Electromagnetic Waves

To produce damped oscillations, circuits must be complex: and . Electromagnetic waves are composed of an electric field and a magnetic field (also known as Hertzian waves).

Wavelength and Dipole Antennas

Wavelength is the distance a wave travels during one complete cycle, calculated as λ = c / f. A dipole is a half-wavelength antenna consisting of two symmetrical conductors. In a half-wave dipole, the length between its ends coincides with half the wavelength of the target frequency.

Radiation Resistance and Polarization

Radiation resistance is the resistance of the dipole at resonance, typically 75Ω. The polarization radiation diagram defines the direction of the electric field of the electromagnetic... Continue reading "Fundamentals of Electromagnetic Waves and Satellite Systems" »

The Electromagnetic Spectrum

In a vacuum, electromagnetic waves move at the same speed and differ from each other by their frequency. They are classified by the frequency of the electromagnetic spectrum.

Frequency Classifications

• Radio Waves: Thousands of Hertz (kHz) are considered very low frequency.
• AM Radio: One million Hertz (MHz).
• TV Band: Very high frequency (VHF) waves begin at about 50 MHz.
• FM Radio: Operates between 88-108 MHz.
• UHF: Ultra-high frequency waves.
• Microwaves and Infrared: Often referred to as heat waves.

Visible Light and Higher Frequencies

Visible light constitutes less than a millionth of 1% of the electromagnetic spectrum. The minimum frequency visible to the human eye is red, while the maximum frequency is nearly twice that... Continue reading "Understanding the Electromagnetic Spectrum and Relativity" »

Acoustics and Noise Principles

1. What is sound, from a technical perspective?

Answer: Sound is a mechanical vibration of a physical medium. It is a longitudinal wave that travels through the air.

2. When addressing a noise problem, what measures can be taken? Explain clearly.

Answer: Isolate the source with a solid, low-density material.

3. My neighbor's stereo is at 40 dB:

Answer: Chilean law considers a maximum of 45 dB between 9 PM (21:00 hrs) and 7 AM (07:00 hrs). Therefore, a personal solution would involve covering my ears or isolating my room.

4. A sound pressure measured in atmospheres is 2 atm. Calculate the noise intensity and discuss the obtained value.

5. Name three standards that can be referenced to solve a neighborhood noise problem:

Understanding Light: Key Optical Concepts

Index of Refraction

We define the index of refraction (n) of a medium as the ratio between the speed of light in a vacuum (c) and the speed of light in that medium (v):

n = c / v

Laws of Reflection of Light

When light rays strike a surface, they undergo a rebound that follows these laws:

1. The incident ray, the normal to the surface, and the reflected ray all lie in the same plane.
2. The angle of incidence (i) is equal to the angle of reflection (r), and they are on opposite sides of the normal: i = r.

Laws of Refraction of Light

When light passes from one transparent medium to another where the speed of light changes, its direction also changes. This phenomenon is known as the refraction of light, governed by these... Continue reading "Fundamentals of Light: Reflection, Refraction, and Lenses" »

The Nature of Light and Electromagnetic Waves

All radiation propagates in waves. Radiation or waves can propagate through a vacuum, transporting energy. The energy of these waves is directly proportional to their frequency, forming the electromagnetic spectrum. The visible light spectrum consists of electromagnetic waves that human eyes can capture.

Properties of Light

• Straight-line propagation: Light travels in a straight line.
• Reflection: Light reflects when it reaches a reflective surface.
• Refraction: Light changes direction when passing from one medium to another.
• Dispersion: Light can be separated into its component colors.

A ray is the straight line that graphically represents the direction of light propagation.

Shadows and Eclipses

If a light... Continue reading "Understanding Light: Properties, Reflection, and Refraction" »

Definitions AC. The changing of direction.
CURRENT. The meaning does not change, but may change in value. CURRENT PERIODIC. That which is repeated in cycles with the same period. PERIOD. Time it takes one cycle. CYCLE. Set starting values such that at any one walking back to the all the values of the signal. FREQUENCY. Number of cycles a second. The unit hertz. Resonance frequency is that frequency that makes a circuit is resistive (the circuit contains inductors and capacitors). Or half-power frequency cut-off frequency filter. That often happens in these situations simultaneously: the power half the maximum, the load voltage is 70% of the maximum, the phase angle is 45 degrees. BANDWIDTH. Difference between the cutoff frequencies. OR QUALITY