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

Human Evolution: From *Orrorin* to *Homo Sapiens*

The Earth was formed 4,500 million years ago. There is evidence that the hominid family emerged 6 million years ago, with our species, Homo sapiens sapiens, appearing only 150,000 years ago. Our species is characterized by the development of the brain, which allows for complex social behavior, consciousness of our own existence, and a great capacity for communication. The evolution of our species includes the following:

Key Hominid Species

1. Orrorin tugenensis: Lived more than 6 million years ago (MA). They were omnivorous, lived in jungles, measured 1.4 meters, were bipedal, and were descendants of the current chimpanzees, but with differences in the pelvis, humerus, and femur.
2. Ardipithecus ramidus:

Deriving Key Physics Formulas

Deriving v = u + at

    → v = u + at

Deriving s = ut + ½ at²

V_average =     But v = u + at       → V_average =  

V_average = s/t    → s = V_average(t)    → s = (t)     → s = ut + ½ at²

Deriving v² = u² + 2as

v = u + at   → v² = u² + 2uat + (at)²    {multiply out both sides}

We can rewrite this as v² = u² + 2a(ut + ½ at²)             {because 2a(ut + ½ at²) = 2uat + (at)²}

Now sub in s = ut + ½ at²    → v² = u² + 2as

Force and Motion

- F = Bqv: Consider a section of conductor of length l through which a current I is flowing.

If q is the charge which carries the current in this section of the conductor, then:

I = q/t, where t is the time it takes the charge q to travel

In the Beginning

Certain questions about our existence on Earth are so fundamental that they have been incorporated into religious mythologies. These questions not only concern the origin of the Earth and the evolution of life but also extend to the origin of the universe and to the nature of space and time. Did the universe have a beginning, and will it ever end? What existed before the universe formed? Does the universe have limits, and what exists beyond those limits? It is proper to raise these questions at the beginning of a geochemistry course because they are within the scope of cosmochemistry.

The Big Bang

The universe started like a bubble in a stream. At first, it was not there, and suddenly it formed and expanded rapidly as though it... Continue reading "Cosmochemistry: Unveiling the Universe's Origin and Evolution" »

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" »

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 / √(

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:

Understanding Temperature and Heat

Temperature: A measure of the average kinetic energy of the particles in a substance, perceived through our sense of touch as hot or cold. It reflects the internal energy level of a body.

Heat Transfer Methods

Heat can be transferred through three primary methods:

• Conduction: Heat transfer through direct contact.
• Convection: Heat transfer through the movement of fluids (liquids or gases).
• Radiation: Heat transfer through electromagnetic waves.

Units of Heat

• Calorie: The amount of heat required to raise the temperature of one gram of water by one degree Celsius.
• BTU (British Thermal Unit): The amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit.

Thermal Expansion

• Linear Expansion: