2026 Physical Science Final Exam Review Flashcards

Planetary Orientation and Seasonal Variations

The orientation of the Earth in space is defined by its axis, which is the imaginary line around which the planet rotates. This axis is tilted at an angle relative to the Sun. On a standard diagram of the Earth, the Equator is the central horizontal line dividing the planet into Northern and Southern Hemispheres. Typical geographical points of interest include the North Pole at the top of the axis, the South Pole at the bottom, and the location of the state of Connecticut in the Northern Hemisphere. Outside the Earth's immediate orbital path, the North Star (Polaris) remains a fixed reference point toward which the Earth's North Pole is always aimed.

Seasonal variation is most clearly understood by looking at specific months like January and July across different latitudes. In January, the North Pole experiences $0\,\text{hrs}$ of sunlight and receives indirect light, resulting in a winter season with extremely cold conditions. During this same month, Connecticut receives approximately $9\,\text{hrs}$ of sunlight; the light is indirect, leading to a cold winter. At the Equator, there are $12\,\text{hrs}$ of sunlight delivered via direct rays, maintaining a warm climate year-round. In contrast, the South Pole in January experiences $24\,\text{hrs}$ of sunlight. This light is direct, resulting in a summer season that is cold but milder than the South Pole's winter.

In July, the conditions shift significantly. The North Pole experiences $24\,\text{hrs}$ of direct sunlight, causing a summer season that is cold but warmer than its winter. Connecticut receives approximately $15\,\text{hrs}$ of direct sunlight, resulting in a warm summer. The Equator maintains its consistent $12\,\text{hrs}$ of sunlight, although it is categorized as indirect during this period, keeping the climate warm year-round. The South Pole during July experiences $0\,\text{hrs}$ of sunlight delivered indirectly, which creates an extremely cold winter.

During transitional months such as March, the distribution of sunlight becomes more uniform. The North Pole, Connecticut, the Equator, and the South Pole all receive approximately $12\,\text{hrs}$ of sunlight. In the North Pole, this light is indirect, and the climate remains very cold. In Connecticut, the sunlight is direct, leading to cool-to-mild temperatures. The Equator receives direct light and stays warm, while the South Pole receives indirect light and remains cold.

Global Climates and Axial Tilt Mechanics

The difference in temperature between Connecticut and the North Pole during the summer is explained by the duration and intensity of sunlight. While both locations receive many hours of daylight, Connecticut receives more direct sunlight. Direct sunlight concentrates energy over a smaller surface area, heating the ground more effectively. At the North Pole, sunlight arrives at a low angle, meaning the solar energy is spread out over a larger area, which prevents the surface from warming significantly despite the long duration of daylight.

A common scientific misconception is that the distance between the Earth and the Sun explains the seasons. This claim is disproven by the observation that seasons occur at opposite times in the Northern and Southern Hemispheres. Furthermore, Earth is actually closer to the Sun during the Northern Hemisphere's winter and farther away during its summer. The primary cause of the seasons is the Earth's axial tilt. This tilt changes the angle and duration of sunlight throughout the year. More direct sunlight and longer days create warmer temperatures, whereas less direct sunlight and shorter days result in colder temperatures.

The mechanical difference between direct and indirect sunlight centers on energy concentration. Direct sunlight hits the Earth's surface at a steep angle, concentrating energy in a smaller area. Indirect sunlight hits at a shallow angle, spreading the same amount of energy over a much larger surface area, which results in lower temperatures.

Earth's Motion: Rotation and Revolution

Rotation refers to the Earth's movement as it spins on its central axis. It takes approximately $24\,\text{hours}$ to complete one full rotation. This motion is responsible for the cycle of day and night; day occurs when a side of the Earth faces the Sun, while night occurs when that side faces away from the Sun.

Revolution is the movement of the Earth as it orbits around the Sun. It takes approximately $365\,\text{days}$ to complete one full orbit. One complete revolution is defined as one year. This orbital movement, combined with the Earth's axial tilt, is what causes the change in seasons.

Weather versus Climate

Weather represents short-term atmospheric conditions that change on a daily or hourly basis. Examples of weather include specific statements like "it is raining today" or "today's temperature is $75\,\text{°F}$."

In contrast, climate refers to long-term weather patterns that change over decades rather than days. Climate describes the general expectations for a region, such as the fact that Connecticut has four distinct seasons or that the Sahara Desert is characterized as hot and dry.

Climate Change and the Greenhouse Effect

Greenhouse gases are atmospheric components that impact global temperatures. Three primary examples of these gases include Methane, Carbon dioxide ($CO_2$), and Nitrous oxide. These gases influence the planet's temperature through a specific mechanism: when fossil fuels are burned, they release these gases into the atmosphere. They act like a cover over the Earth, trapping heat radiated from the Sun while allowing solar light to pass through. This trapped heat leads to an overall increase in the planet's temperature.

Albedo and Light Interaction

Albedo is a measure of how much light and heat a surface reflects. Surfaces are categorized into low and high albedo. Low albedo surfaces are dark-colored and absorb most light and heat; examples include asphalt, black wool, and tar. These surfaces have a value closer to $0$. High albedo surfaces are light-colored and reflect most light and heat; examples include sand, glass, and grass. These surfaces have a value closer to $1$. This concept explains why the North Pole remains frozen even during its summer: the thick layers of ice and snow are white, giving them a high albedo that reflects the Sun's light and heat back into space.

Light also interacts with surfaces through reflection and refraction. Reflection occurs when light bounces off a surface. Refraction is the process where light bends as it passes from one medium to another.

Thermal Energy and Temperature Conversions

Temperature is defined as the amount of kinetic energy that the atoms or molecules within an object possess. There are three primary scales for measuring this energy: Celsius ($\text{°C}$), Fahrenheit ($\text{°F}$), and Kelvin ($K$). The following formulas are used for conversions:

$\text{°C} = (\text{°F} - 32) \div 1.8$

$\text{°F} = (1.8 \times \text{°C}) + 32$

$K = \text{°C} + 273$

$\text{°C} = K - 273$

Using these formulas, specific values can be calculated. For instance, $50\,\text{°C}$ is equivalent to $323.15\,K$ (using the more precise constant) and $122\,\text{°F}$. A temperature of $200\,\text{°F}$ converts to $93.33\,\text{°C}$ and $366.48\,K$. Finally, $273\,K$ is approximately $-0.15\,\text{°C}$ (noting that $0\,\text{°C}$ is exactly $273.15\,K$) and $31.73\,\text{°F}$. The difference between $0\,\text{°C}$ and $0\,K$ is fundamental: $0\,\text{°C}$ is the freezing point of water, whereas $0\,K$ (Absolute Zero) represents the lowest possible theoretical temperature where molecular motion ceases.

Modes of Heat Transfer

Heat is transferred through three primary modes: conduction, convection, and radiation. Conduction is the transfer of heat from one medium to another through direct contact, such as a stove fire heating a pan, a pan warming the surrounding air, or warm juice melting ice. Convection is the flow of heat through fluids like air or water. Examples include a window opening on a hot day to allow air into a cold room, convection currents in the Earth's lithosphere moving tectonic plates, or the Sun heating the Earth unevenly, causing warm, less dense air to rise and cooler, denser air to sink. Radiation is the heat energy emitted by an object in the form of waves, such as the heat from the Sun, the heat given off by a fire, or the heat emitted by hot steel.

These modes can be illustrated through the process of heating a s'more. In conduction, heat moves from the outside of the marshmallow to melt the inside. In convection, the fire heats the air, causing hot air and smoke to rise straight up to cook a marshmallow held directly above the flame. In radiation, the glowing fire emits invisible infrared waves in all surrounding directions.

Specific Heat and Material Characteristics

Specific heat is defined as the amount of heat energy required to raise the temperature of $1\,\text{gram}$ of a substance by $1\,\text{°C}$. Materials with low specific heat warm up and cool down quickly because they require less energy to change temperature, while materials with high specific heat change temperature slowly.

In a comparison between aluminum and tin, tin will experience a faster and greater rise in temperature. This is because tin has a low specific heat ($0.213\,J/g \cdot \text{°C}$), meaning its atoms require less energy to heat up. Aluminum has a much higher specific heat ($0.902\,J/g \cdot \text{°C}$) and will take more time and energy to reach the same temperature.

The specific heat capacities ($J/g \cdot \text{°C}$) for common substances are as follows: Liquid Water ($4.184$), Ice at $0\,\text{°C}$ ($2.010$), Steam at $100\,\text{°C}$ ($1.996$), Aluminum ($0.902$), Magnesium ($1.020$), Chromium ($0.461$), Zinc ($0.387$), Tin ($0.213$), Mercury ($0.140$), and Lead ($0.128$).

Wave Properties and Sound Mechanics

Waves are characterized by several physical properties. The crest is the highest point of an individual wave, while the trough is the lowest point. The amplitude is the vertical height of the wave measured from the middle equilibrium line to either the crest or the trough. Wavelength is the horizontal distance measured from one peak (crest) to the next consecutive peak.

Waves are categorized into two main types: transverse and longitudinal. Transverse waves appear as a "wavy line" where the medium moves perpendicular to the wave direction. Longitudinal waves move by pushing back and forth. They consist of compressions, where the wave medium is squeezed tightly together, and rarefactions, where the medium is stretched far apart.

The Electromagnetic Spectrum

The Electromagnetic (EM) Spectrum organizes light waves by their physical properties. On one end of the spectrum are Gamma rays, which have the highest energy, the shortest wavelength ($0.0001\,\text{nm}$), and the highest frequency. On the opposite end are radio waves, which have the lowest energy, the longest wavelength ($100\,\text{m}$), and the lowest frequency. The spectrum includes, from shortest to longest wavelength: Gamma rays, X-rays ($0.01\,\text{nm}$), Ultraviolet (UV) ($10\,\text{nm}$), Visible light ($400\text{--}700\,\text{nm}$), Infrared ($1000\,\text{nm}$), Radar/TV ($1\,\text{cm}$), and Radio waves ($AM/FM$).

Mechanical and Compositional Layers of the Earth

Earth's layers can be classified in two ways: compositionally (what they are made of) and mechanically (how they behave). Compositional layers are defined by their chemical makeup, such as iron and nickel content. Mechanical layers are defined by their physical state, such as being solid, liquid, or gas-like.

There are five distinct mechanical layers. The Lithosphere is the solid outer crust of the Earth. Beneath it lies the Asthenosphere, which is soft and flows slowly. The Mesosphere is a dense, rigid layer of rock under immense pressure. The Outer Core is a liquid layer composed of molten iron and nickel. The Inner Core is the innermost layer; it is a solid ball of iron and nickel maintained in a solid state by extreme pressure.

Plate Tectonic Theory and Continental Drift

Plate tectonic theory states that the Earth's outer shell is divided into several large and small plates that glide over the mantle. The interaction of these plates at their boundaries causes major geological events such as earthquakes, volcanic eruptions, and the building of mountains.

This movement is driven by thermal processes. Radiation occurs in the core as it generates heat through radioactive decay, sending energy toward the lower mantle. Convection occurs in the mantle as rock is heated from below, becomes less dense, and rises toward the crust; as it cools near the surface, it becomes denser and sinks, creating a continuous cycle. Conduction transfers heat from the hot mantle to the solid lithospheric plates, which can cause them to expand, weaken, or move.

Continental drift is the specific theory that the Earth's continents were once joined together in a single supercontinent and have since drifted apart across the ocean. This theory was proposed by the scientist Alfred Wegener. Evidence for the existence of the supercontinent, known as Pangea, includes the way the coastlines of South America and Africa fit together like puzzle pieces, the discovery of identical animal and plant fossils on widely separated continents, and the presence of ancient glacial deposits across different continents.

Crustal Composition and Plate Boundaries

Earth's crust is divided into oceanic and continental types. Oceanic crust is thin and high in density, composed mainly of Basalt. Continental crust is thick and lower in density, composed mainly of Granite and Andesite.

There are three types of plate boundaries. Convergent boundaries occur where plates move toward each other ($\rightarrow \leftarrow$), resulting in deep ocean trenches and volcanic mountain ranges. Divergent boundaries occur where plates move apart ($\leftarrow \rightarrow$), creating mid-ocean ridges, rift valleys, and new seafloor. Transform boundaries occur when plates slide past each other ($\rightarrow \leftarrow$ vertically), resulting in fault lines and frequent earthquakes.

Earthquakes can happen at all boundaries but are most frequent at transform and convergent sites. They originate at a focal point underground, while the strongest shaking is felt at the epicenter on the surface. Scientists use data from at least three different cities to triangulate the exact location of an epicenter. A specific example of a boundary is the interaction between the Nazca plate and the South American plate. This is a convergent boundary (oceanic-continental) where subduction occurs; the denser oceanic Nazca plate sinks under the less dense continental South American plate. This creates the Peru-Chile Trench and the Andes mountains. Seafloor spreading does not occur here, as that process is exclusive to divergent boundaries.

Supervolcano eruptions at these boundaries have massive impacts. Locally, they cause the destruction of ecosystems and infrastructure and release toxic gases and ash. Globally, the release of sulfur dioxide ($SO_2$) into the stratosphere blocks sunlight, leading to a "volcanic winter" that drops temperatures, destroys agriculture, and causes mass famine.

The Rock Cycle and Igneous Formations

Rocks are classified into three types based on their formation. Sedimentary rocks form through weathering, erosion, and the compaction and cementation of sediment. They often contain fossils and are found in locations like beaches; they have visible layers and a grainy texture. Metamorphic rocks form through heat and pressure, often in subduction zones; they are identified by foliation, high density, and crystals. Igneous rocks form through the melting and cooling of rock in volcanoes.

Igneous rocks are further divided into intrusive and extrusive. Intrusive rocks form extremely slowly deep underground, resulting in a coarse-grained texture with large, visible crystals. Extrusive rocks form very fast on the Earth's surface, resulting in a fine-grained texture with microscopic crystals, a glassy texture (like obsidian), or air holes.

Weathering, Erosion, and Deposition

Weathering is the process of breaking down rocks into smaller pieces. Erosion is the transport of those rock pieces by wind, water, ice, or gravity. Deposition occurs when those traveling particles settle and drop into a new location. Water is considered the most effective agent of erosion.

Weathering is categorized as either physical or chemical. Physical (mechanical) weathering breaks rocks into smaller fragments without changing their chemical makeup; examples include frost wedging, root wedging, and abrasion. Chemical weathering involves chemical reactions that alter the rock's composition and atomic structure; examples include rusting, hydrolysis, and acid rain dissolving limestone. Plants can accelerate weathering when their roots grow into fractures and physically force the rock apart.

Chemical Properties of the Environment

The pH scale measures how acidic or basic a substance is. The scale runs from $0$ to $14$. A pH of $0$ is the most acidic (e.g., battery acid), while a pH of $14$ is the most basic (e.g., drain cleaner). A pH of $7$ is neutral (e.g., pure water). Normal rain has a pH of approximately $5.6$. Acid rain is defined as rain with a pH below $5.0$ (typically between $4.0$ and $4.4$).

Acid rain is caused by two main gases: Sulfur dioxide ($SO_2$) and Nitrogen oxides ($NO_x$). $SO_2$ comes from coal-burning power plants, industrial factories, and volcanic eruptions. $NO_x$ comes from vehicle exhaust, burning fossil fuels, and lightning strikes.

The Hydrologic Cycle and Water Distribution

The water cycle involves several key processes. Evaporation occurs when liquid water turns into water vapor gas due to heat. Transpiration is the evaporation of water from plant leaves. Condensation happens when water vapor cools and turns back into liquid droplets to form clouds. Precipitation is any form of water falling from clouds to Earth. Infiltration is water sinking and soaking into the soil, while percolation is the downward movement of filtered water through soil layers and rock into underground aquifers.

The Sun drives the water cycle by providing the thermal energy required for evaporation. Regarding earth's water distribution, most of the Earth's saltwater is found in the global oceans, while the majority of the planet's freshwater is frozen inside ice caps and glaciers.