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

Sound: Concepts and Characteristics

In physics, sound is defined as a periodic perturbation in air. It is a mechanical longitudinal wave, where the motion of particles in the medium travels in the same direction as the wave, which propagates through an elastic medium. This periodic perturbation originates sound waves.

For sound to be produced, there must be vibrating matter and an elastic medium. For example, a guitar's vibrating strings produce sound.

Speed of Sound

The speed of sound (v) is calculated depending on the medium of propagation. In air, its speed is 331 m/s at 0°C and 1 atm. To estimate the speed of sound in air at different temperatures, the following formula is used:

Where temperature is measured in °C.

Speed of Sound in Various

2.1 Thermodynamics: Concepts

Thermodynamics is a science that studies energy and its transformations.
A thermodynamic property is a system’s characteristic that does not depend on history. There are two types of thermodynamic properties: intensive and extensive properties. The intensive property is independent of the mass or size of the system (e.g., temperature, pressure, and density), whereas an extensive property is dependent (e.g., mass, weight, volume, and total energy).

A system is in thermal equilibrium when the temperature is uniform.
2.2 Zeroth Law of Thermodynamics

If two bodies are in thermal equilibrium with a third one, then all three are in thermal equilibrium with each other.

Remember that thermal equilibrium occurs when the temperature... Continue reading "Understanding Thermodynamics and Wave Motion Concepts" »

Understanding Structures: Definition and Types

A structure is the set of elements intended to resist the forces acting upon it, providing rigidity and maintaining its shape.

Examples of Structures

Natural Structures

• Trees
• Bones
• Spiderwebs

Artificial Structures

• Buildings
• Bridges
• Furniture

Types of Artificial Structures

Framework Structures

These structures form the skeletal framework of an object, providing its primary support and shape.

Laminar or Plate Structures

These structures surround and protect an object, typically composed of thin sheets of metal, plastic, or similar materials.

Forces and Stresses on Structures

Key Concepts: Force, Load, and Stress

Defining Force

A force is any influence that can deform a body (a static effect) or alter its state of motion... Continue reading "Structural Engineering Fundamentals: Forces, Stresses, and Design Principles" »

Analysis of "On Home Beaches" by Les Murray

Body Image in a Consumerist Society

Les Murray's poem "On Home Beaches" explores the theme of body image and its significance in a consumerist society. It highlights the humiliation faced by individuals who do not conform to conventional beauty standards, particularly in environments like beaches where bodies are exposed.

Subverting the Sonnet Form

The poem adopts the sonnet form, traditionally associated with love and tenderness. Murray ironically subverts this form by using it to depict mortification and ridicule, contrasting the conventional themes of love with the harsh realities of body shaming.

Imagery of the Seaside

The poem utilizes vivid imagery of the seaside, including sand, towels, waves, foam,... Continue reading "Body Image and the Outback in Australian Poetry: Analysis of Les Murray and Henry Lawson" »

Electromagnetic Wave Fundamentals

An electromagnetic wave is a disturbance that propagates through space due to the simultaneous oscillation of electric and magnetic fields. Unlike mechanical waves, they do not require a medium for propagation and can travel through a vacuum.

Properties of Electromagnetic Waves:

• They travel at the speed of light (c) in a vacuum (approximately 3 x 10⁸ m/s).
• They exhibit typical wave properties, such as interference and diffraction.
• Wavelength (λ) and frequency (f) are related by the equation: c = λf.

Examples include: visible light, radio waves, TV waves, microwaves, and X-rays.

The Speed of Light in Vacuum

The propagation speed (c) of electromagnetic waves in a vacuum is calculated using the formula:

c = 1 / √(

The Atom: The Building Block of Electricity

Understanding the atom is important for an effective study of electricity. Everything around us is made of atoms. In the middle of each atom is a nucleus, which contains two kinds of tiny particles called protons and neutrons. Orbiting the nucleus are even smaller particles called electrons.

Atomic Structure and Charge

A model of the atom is similar to our solar system. The nucleus is in the center of the atom, like the sun is in the center of the solar system. The electrons orbit the nucleus, much like the planets orbit the sun.

• Protons have what we call a positive (+) charge.
• Electrons have a negative (-) charge.
• Neutrons have no charge; they are neutral.

Normally, atoms are neutral. That is to say, they... Continue reading "Fundamentals of Electricity: Atoms, Circuits, and Current" »

Refraction of Light: Principles and Elements

Refraction of light is the change in direction experienced by light rays when they pass through a surface separating two media of different densities.

Key Elements of Light Refraction

• Incident Ray: The ray of light that reaches the surface in medium 1.
• Refracted Ray: The ray of light that has crossed the surface and moves in medium 2.
• Normal: An imaginary straight line perpendicular to the surface at the point of incidence.
• Incident Angle: The angle formed between the incident ray and the normal.
• Angle of Refraction: The angle formed by the refracted ray and the normal.

Conditions Governing Light Refraction

In the process of refraction, the following conditions apply:

• When light passes from a less dense medium

Light Source

A light source is an object that emits light. There are natural light sources and artificial light sources. Examples of natural light sources include the Sun and stars, while an example of an artificial light source is a light bulb.

Luminous Bodies

Luminous bodies possess the characteristic of emitting light themselves, such as the Sun or the flame of a candle.

Illuminated Bodies

Illuminated bodies do not produce light but receive it from another body and are able to reflect it. Examples include the Moon, a desk, or a wall.

Opaque Bodies

Opaque bodies do not allow light to pass through them. Examples include a wall or a table.

Translucent Bodies

Translucent bodies allow light to pass through partially, but the light is diffused so that... Continue reading "Understanding Light: Properties, Reflection, and Mirrors" »

Understanding Solar Radiation

Direct radiation: Solar radiation received directly from the sun without being scattered by the atmosphere.

Diffuse radiation: Solar radiation received after its direction has been changed due to reflection and refraction in the atmosphere.

Total radiation is the sum of direct and diffuse radiation at the surface.

Solar Constant

The solar constant is the amount of energy received per unit time on a unit area perpendicular to the sun's direction at Earth's mean distance, outside the atmosphere. The currently accepted value is: S = 1.94 Ly min^-1 = 1368 W/m²

Absorption, Reflection, and Transmission

When radiation strikes a body, it can be absorbed, reflected, or transmitted. The ratio is: e + r + t = 1, where:

• e = absorptivity
• r

Physical science studies the properties of matter and energy, considering the attributes that can be measured. Physics is an empirical science. All that we know of the physical world and the principles that govern its behavior has been learned through the observation of natural phenomena. The ultimate test of any physical theory is its agreement with observations and measurements. Physics is, therefore, essentially a science of measurement. Examples include matter, energy, measurement, and observation.

Key Concepts in Physics

• Matter: The substance that makes up the physical universe, occupying space and existing in many forms perceivable by the senses.
• Empirical: Based solely on observation and factual experience.

Branches of Physics

• Classical Physics: