Comprehensive Grade 9 Science Review - DepEd MATATAG Curriculum

This flashcard set covers the theoretical foundations of Newtonian mechanics, electrodynamics, circuits, electromagnetic radiation, and lithospheric dynamics with a specific focus on the Philippine tectonic setting as outlined in the Grade 9 Science reviewer.

Newton's First Law of Motion

Also known as the Law of Inertia, it states that an object remains at rest or continues at a constant velocity unless acted upon by a net external, unbalanced force ($\sum F = 0$).

Inertia

An intrinsic physical property of matter that quantifies an object's natural resistance to changes in its state of motion, directly proportional to its mass.

Mass

An invariant scalar quantity reflecting the total matter within a body, measured in kilograms ($kg$).

Weight ($W$)

A vector quantity representing the localized gravitational force exerted on a mass ($W = mg$), where $g \thickapprox 9.81\,m/s^2$ on Earth.

Static Equilibrium

A state where an object is at rest with zero net force ($\sum F = 0$) and zero velocity ($v = 0$).

Dynamic Equilibrium

A state where an object travels at a constant velocity along a straight line under zero net force.

Newton's Second Law of Motion

The Law of Acceleration, which states that net force equals mass times acceleration ($\sum F = ma$).

Newton ($N$)

The standard SI unit of force, defined as the force required to accelerate a one-kilogram mass at a rate of one meter per second squared ($1\,N = 1\,kg \cdot m/s^2$).

Newton's Third Law of Motion

The Law of Interaction, stating that for every action force, there is an equal and opposite reaction force acting on separate objects ($F_{A\text{ on }B} = -F_{B\text{ on }A}$).

Electric Current ($I$)

The time rate of electric charge flow passing through a conductor ($I = \Delta Q / \Delta t$), measured in Amperes ($A$).

Conventional Current

The flow of charge defined as moving from positive potential to negative potential, which is opposite to actual electron flow.

Voltage ($V$)

Also called electric potential difference, it quantifies the work required per unit charge to move a charge between two points ($V = W / Q$), measured in Volts ($V$).

Resistance ($R$)

The quantification of a material's opposition to current flow, measured in Ohms ($\Omega$).

Ohm's Law

States that current is directly proportional to voltage and inversely proportional to resistance ($I = V / R$), provided physical conditions like temperature remain constant.

Series Circuit

A topology where components are arranged end-to-end in a single path, meaning current is uniform ($I_{total} = I_1 = I_2$) and total resistance is the sum of all individual resistances ($R_{eq} = \sum R_i$).

Parallel Circuit

A topology where components are connected across common junctions, meaning voltage is uniform ($V_{total} = V_1 = V_2$) and the reciprocal of equivalent resistance is the sum of the reciprocals of branch resistances ($1/R_{eq} = \sum 1/R_i$).

Short Circuit

A condition where an unintended low-resistance path bypasses a load, causing resistance to drop near zero ($R \rightarrow 0$) and current to spike to hazardous levels ($I \rightarrow \infty$).

Ground Fault Circuit Interrupter (GFCI)

A safety device that monitors current balance and rapidly opens the circuit upon detecting leakage currents between $\sim 4$ to $6\,mA$ flowing to ground.

Electromagnetic Radiation (EMR)

Self-propagating transverse waves composed of mutually perpendicular oscillating electric ($E$) and magnetic ($B$) fields.

Speed of Light ($c$)

The constant velocity of all electromagnetic waves in a vacuum, approximately $3.00 \times 10^8\,m/s$.

Planck's Constant ($h$)

A physical constant ($h \thickapprox 6.626 \times 10^{-34}\,J \cdot s$) used to relate photon energy to frequency ($E = hf$).

Ionizing Radiation

Radiation with photon energies exceeding $10$ to $12.6\,eV$ (e.g., UV-B, X-rays, Gamma rays) capable of stripping electrons from atoms and damaging DNA.

Continental Drift Theory

Proposed by Alfred Wegener in 1912, suggesting all continents were once part of a supercontinent named Pangaea.

Pangaea

The Mesozoic supercontinent that began rifting apart approximately 200 million years ago into Laurasia and Gondwana.

Glossopteris

A heavy-seeded Permian fern fossil found across South America, Africa, India, Australia, and Antarctica, serving as evidence for continental drift.

Slab Pull

The primary driving force of plate motion, where a cooling, dense oceanic plate subducts into the asthenosphere under gravity and pulls the trailing plate.

Divergent Boundary

A plate boundary where plates move apart, resulting in mid-ocean ridges, rift valleys, and seafloor spreading.

Convergent Boundary (Continental-Continental)

A collision of two continental plates causing crustal thickening and non-volcanic mountain ranges, such as the Himalayan Orogenic Belt.

Philippine Mobile Belt (PMB)

The central structural framework of the Philippine archipelago, situated between the Philippine Sea Plate and the Sunda Block.

Philippine Fault Zone (PFZ)

A $1,200$-kilometer-long left-lateral (sinistral) strike-slip fault system traversing the archipelago from northwestern Luzon to eastern Mindanao.

Galathea Depth

The deepest point of the Philippine Trench, reaching depths greater than $10,500$ meters.