Comprehensive Science Review: Dynamic Earth, Chemistry, Universe, and Motion Physics

Comprehensive practice flashcards covering Dynamic Earth and Plate Tectonics, Nuclear and Reaction Chemistry, Astrophysics and the Big Bang, and Motion Physics based on detailed lecture notes.

Who proposed the Theory of Continental Drift in $1912$, and what did it suggest?

Alfred Wegener proposed the theory, suggesting that continents were not fixed in place but rather slowly moving across the Earth's surface over time.

According to Alfred Wegener, what was the initial supercontinent called when all continents were conjoint?

Pangea.

How does fossil evidence of the Mesosaurus support the Theory of Continental Drift?

The Mesosaurus was a small, freshwater reptile that lived $250\,\text{million years}$ ago whose fossils are only found in South America and southern Africa; because it could not swim across the Atlantic Ocean, the two continents must have once been joined.

What paleoclimate evidence was documented to support the Theory of Continental Drift?

Fossil and glacial deposits are found on continents that are now located near the equator.

What does SONAR stand for, and how does it measure ocean depth?

SONAR stands for sound navigation and ranging; a ship sends out a sound pulse, calculates the time required for it to return, and calculates how deep the water is.

What three major underwater features were discovered using SONAR in the mid-$20^{\text{th}}$ century?

1. Mid-ocean ridges (long underwater mountains), 2. Deep-sea trenches (narrow, deep valleys on the ocean floor), and 3. Rift valleys (central cracks along mid-ocean ridges).

What is seafloor spreading?

The process in which new oceanic crust forms at mid-ocean ridges and slowly moves outward, providing a mechanism for continental drift.

What are the six sequential steps in the process of seafloor spreading?

1. Convection currents cause magma to rise through cracks at mid-ocean ridges. 2. Magma reaches the ocean floor, cools, and solidifies, creating new crust. 3. New crust pushes older crust away to both sides. 4. This causes the spread of the ocean floor. 5. Old crust subducts against continental crust. 6. Subducted crust melts back into the mantle.

What drives mantle convection currents?

Heat rising from the Earth's core drives the circular movement of magma; as magma rises toward oceanic ridges, it cools and sinks again because colder magma is more dense, establishing a continuous flow.

What happens at divergent (constructive) plate boundaries, and what features do they form?

Plates move away from one another, allowing magma to rise and solidify into new crust (seafloor spreading); this forms mid-ocean ridges and rift valleys.

What occurs at transform plate boundaries?

Plates slide past each other horizontally; no new crust is created or destroyed, but built-up shearing stress leads to earthquakes along fault lines.

What geological events occur at an oceanic-continental convergent boundary?

The denser oceanic plate subducts underneath the less dense continental plate, creating a subduction zone with earthquakes and a volcanic arc parallel to the continental plate.

What occurs when two continental plates collide at a convergent boundary?

Because both plates have similar densities, the collision compresses and folds the crust to form mountain ranges.

What causes normal, reverse, and strike-slip faults, respectively?

Normal faults are caused by tensional stress (pulling apart, one plate shifts downward); reverse faults are caused by compressional stress (pushing together, one is pushed above the other); strike-slip faults are caused by shearing stress (sliding past horizontally).

What is the difference between a graben fault and a horst fault?

A graben fault is a block of land that has dropped down between two parallel faults, whereas a horst fault is a block of land that was raised.

What is the difference between the focus and the epicenter of an earthquake?

The focus is the point underground where the earthquake begins, while the epicenter is the point on the Earth's surface directly above the focus.

How do earthquake magnitude and intensity differ in measurement?

Magnitude measures the amount of energy released using the Moment Magnitude Scale ($M_w$), whereas intensity measures the observed effects on people, buildings, and the environment using the Modified Mercalli Intensity scale.

How do P-waves and S-waves differ in motion and ability to travel through matter?

P (primary/compressional) waves are the fastest, travel through solids, liquids, and gases, and move compressively. S (secondary/transverse) waves are slower, move side-to-side, and travel through solids but not liquids (which proved Earth's outer core is liquid).

What are the two types of surface waves, and how do they rank in speed compared to body waves?

Love waves (horizontal side-to-side motion) and Rayleigh waves (rolling elliptical motion up, down, forwards, and backwards); speed ranks as: Rayleigh waves < Love waves < Body waves.

What are the key characteristics of shield, cinder cone, and composite volcanoes?

Shield volcanoes have repeated, gentle eruptions and gently sloping sides with large footprints. Cinder cone volcanoes erupt explosively with gas-rich magma, forming small, steep-sided cones. Composite volcanoes feature alternating layers of lava and ash, tall symmetrical cones, and viscous silica-rich magma.

How do alpha, beta, and gamma decay affect atomic and mass numbers?

In alpha decay, mass number decreases by $4$ and atomic number decreases by $2$. In beta decay, mass number remains the same and atomic number increases by $1$. In gamma decay, there is no change in either mass number or atomic number.

What materials stop alpha, beta, and gamma radiation, and what is one application of each?

Alpha is stopped by paper (used in smoke detectors); beta is stopped by aluminum (used in targeted cancer treatment); gamma is stopped by lead (used to sterilize hospital equipment and food).

How do energy diagrams distinguish exothermic and endothermic reactions?

In exothermic reactions, reactants have higher chemical potential energy than products, releasing energy ($\Delta H < 0$); in endothermic reactions, reactants have lower energy than products, absorbing energy ($\Delta H > 0$).

What are the general word equations for the three acid reactions covered in the notes?

1. Metal + Acid $\rightarrow$ Salt + Hydrogen. 2. Acid + Base $\rightarrow$ Salt + Water. 3. Acid + Carbonate $\rightarrow$ Salt + Water + Carbon dioxide.

What differentiates complete combustion from incomplete combustion?

Complete combustion occurs with sufficient oxygen to produce carbon dioxide and water ($\text{CH}_{4(g)} + 2\text{O}_{2(g)} \rightarrow \text{CO}_{2(g)} + 2\text{H}_2\text{O}_{(l)}$); incomplete combustion occurs with insufficient oxygen, producing water alongside toxic carbon monoxide ($\text{CO}$) or carbon soot ($\text{C}$).

What are the balanced equations for photosynthesis and cellular respiration?

Photosynthesis (endothermic): $6\text{CO}_2 + 6\text{H}_2\text{O} + \text{energy} \rightarrow \text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2$. Cellular respiration (exothermic): $\text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2 \rightarrow 6\text{CO}_2 + 6\text{H}_2\text{O} + \text{energy}$.

What are the definitions and values in meters for an Astronomical Unit ($\text{AU}$), a light-year ($\text{LY}$), and a parsec ($\text{pc}$)?

$1\,\text{AU} = 1.496 \times 10^{11}\,\text{m}$ (average distance between centre of Earth and centre of Sun); $1\,\text{LY} = 9.47 \times 10^{15}\,\text{m}$ (distance light travels in a year); $1\,\text{pc} = 3.086 \times 10^{16}\,\text{m}$ (distance at which $1\,\text{AU}$ subtends $1\,\text{arcsecond}$, given by $d = \frac{1}{p}$).

What is stellar luminosity, and what is the value of solar luminosity ($L_0$)?

Luminosity is the constant emission of visible light, defined as $L = \frac{\text{Energy}}{\text{Time}}$ in units of $\text{J/s}$ or $\text{Watts}$; solar luminosity is $L_0 = 3.83 \times 10^{26}\,\text{W}$.

How is intensity related to distance from a star according to the inverse square law?

Intensity is luminosity per unit area at a given distance and is inversely proportional to distance squared ($I \propto \frac{1}{d^2}$), which gives the relation $I_1(d_1)^2 = I_2(d_2)^2$.

What does Wien's law state regarding star color and temperature?

Wien's law states that hotter stars emit shorter, bluer wavelengths of light, whereas cooler stars emit longer, redder wavelengths ($\uparrow \text{temperature} = \downarrow \text{wavelength}$).

What are the four fundamental forces of nature listed in the notes?

Gravity (force of attraction between two objects, governed by Newton's law of universal gravitation), Electromagnetic force, Strong force, and Weak force.

What is the difference in appearance and formation between absorption and emission spectra?

An absorption spectrum appears as a continuous rainbow crossed by black lines (formed when atoms in cool gases or liquids absorb photons); an emission spectrum appears as a black background with rainbow lines (formed when excited electrons fall to lower energy levels, releasing photons).

What is the Doppler Effect, and what do blue shift and red shift indicate about a star's motion?

The Doppler Effect is the apparent change in frequency/wavelength caused by relative motion between source and observer. Blue shift (shorter wavelength) indicates the star is moving toward us, while red shift (longer wavelength) indicates the star is moving away from us.

What does Hubble's Law state, and what is its equation?

Hubble noticed all galaxies are moving away from Earth and each other, showing that the farther away a galaxy is, the faster it recedes; expressed as $v = H_0 D$, where $v$ is recession velocity, $H_0$ is Hubble's constant, and $D$ is distance from Earth.

What three pieces of evidence support the Big Bang Theory?

1. Red shift in distant galaxies (proves the universe is expanding from a singular hot, dense point). 2. Cosmic Microwave Background Radiation (relic UV radiation that cooled over $13.8\,\text{billion years}$ into microwaves). 3. Percentage of Hydrogen and Helium (cosmic abundance ratios match primordial nuclear fusion).

What lifecycle path does a low-mass star (like the Sun) follow after the main sequence?

When core hydrogen depletes, the star contracts until helium fusion begins, expanding into a Red Giant; when helium is exhausted, the outer layers form a Planetary Nebula while the core contracts into a White Dwarf.

What lifecycle path does a high-mass star follow after the main sequence?

It expands into a Red Supergiant, fusing progressively heavier elements until iron accumulates; once iron stops fusion, the star collapses and explodes as a Supernova, leaving behind either a Neutron Star or, if massive enough, a Black Hole.

What is the difference between scalar and vector quantities?

Scalars have magnitude only (e.g., speed, mass, volume, time, distance); vectors have both magnitude and direction (e.g., velocity, weight, friction, displacement).

How is time calculated using a ticker timer where $1\,\text{tick} = 0.02\,\text{s}$?

$\text{Time} = \text{number of ticks} \times 0.02\,\text{s}$.

What do the slope and area represent on a velocity-time graph?

The slope of a velocity-time graph represents acceleration ($a = \frac{v - u}{t}$), and the area under the graph represents distance travelled or displacement ($s$).

What is the difference between mass and weight, and what formula relates them?

Mass is the amount of matter in a substance and remains constant everywhere ($\text{kg}$); weight is the gravitational force acting on that mass ($\text{N}$), calculated as $W = mg$, where $g$ is gravitational acceleration.

What are Newton's Three Laws of Motion?

1st Law (Inertia): an object remains at rest or in uniform motion unless acted upon by an external unbalanced force. 2nd Law ($F = ma$): acceleration is produced when an unbalanced force acts on a mass. 3rd Law: for every action, there is an equal and opposite reaction.