Study guide
2.2 Physical Science: Matter, Energy, Forces & Motion
Armed Forces Classification Test AFCT
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1 Chapter 1: Guide Scope, AFQT & Service-Specific Policy
1.1 Editorial Scope and Service-Specific AFCT Policy 1.2 AFQT Meaning and Study Priorities 1.3 Service Composites and Targeted Skill Planning 1.4 Format-Agnostic Test Preparation and Pacing
2 Chapter 2: General Science (GS)
2.1 Life Science: Cell Biology, Human Anatomy & Genetics 2.2 Physical Science: Matter, Energy, Forces & Motion 2.3 Earth & Space Science: Geology, Meteorology & Astronomy 2.4 Chemistry Fundamentals: Atomic Structure, Elements & Chemical Reactions
3 Chapter 3: Arithmetic Reasoning (AR)
3.1 Word Problems: Rates, Ratios, Proportions & Percentages 3.2 Financial & Distance Math: Interest, Profit/Loss, Speed & Time 3.3 Work & Mixture Problems: Joint Rates & Percentage Concentrations 3.4 Multi-Step Problem Solving & Algebraic Word Problems
4 Chapter 4: Word Knowledge (WK)
4.1 General Academic & Technical Vocabulary 4.2 Context Clues, Synonyms & Antonyms 4.3 Word Roots, Prefixes & Suffixes (Etymology) 4.4 Advanced Technical & Operational Terminology
5 Chapter 5: Paragraph Comprehension (PC)
5.1 Identifying Main Ideas, Central Themes & Topic Sentences 5.2 Extracting Supporting Details & Factual Information 5.3 Drawing Logical Inferences & Author's Purpose 5.4 Analyzing Text Structure & Drawing Conclusions
6 Chapter 6: Mathematics Knowledge (MK)
6.1 Pre-Algebra & Number Operations: Exponents, Radicals & Order of Operations 6.2 High School Algebra: Linear Equations, Inequalities & Polynomials 6.3 Geometry Fundamentals: Angles, Triangles, Quadrilaterals & Circles 6.4 Coordinate Geometry, Perimeter, Area & Volume Formulas
7 Chapter 7: Electronics Information (EI)
7.1 Electrical Principles: Voltage, Current, Resistance & Ohm's Law (V=IR, P=VI) 7.2 Electric Circuits: Series, Parallel & Combination Circuit Analysis 7.3 Electrical Components: Resistors, Capacitors, Inductors & Transformers 7.4 Electronic Semiconductors, Transistors, Diodes & Logic Gates
8 Chapter 8: Auto & Shop Information (AS)
8.1 Automotive Systems: Internal Combustion Engines, Fuel & Ignition Systems 8.2 Automotive Mechanical Systems: Transmission, Suspension, Brakes & Cooling 8.3 Hand & Power Tools: Identification, Uses & Fasteners 8.4 Shop Practice, Woodworking, Metalworking & Safety Rules
9 Chapter 9: Mechanical Comprehension (MC)
9.1 Simple Machines: Levers, Pulleys, Inclined Planes & Mechanical Advantage 9.2 Force, Motion, Work & Power: Newton's Laws & Energy Transformations 9.3 Fluid Dynamics & Pressure: Pascal's Principle, Hydraulics & Pneumatics 9.4 Mechanical Components: Gears, Belts, Springs & Friction
10 Chapter 10: Spatial Assembly Practice (AO Skill)
10.1 Spatial Connections and Assembly Patterns
2.2 Physical Science: Matter, Energy, Forces & Motion
Key Takeaways Explain This Topic AI
Matter exists in four primary physical states (solid, liquid, gas, plasma); physical phase changes alter state without changing molecular composition, while chemical changes alter chemical bonds to create new substances.
Newton's Three Laws of Motion describe classical mechanics: Inertia (1st Law), F = m a F = ma F = ma (2nd Law), and Action-Reaction (3rd Law).
Energy cannot be created or destroyed (Law of Conservation of Energy), but transforms between potential energy ( P E = m g h PE = mgh PE = m g h ) and kinetic energy ( K E = 1 2 m v 2 KE = \frac{1}{2}mv^2 K E = 2 1 m v 2 ).
Wave motion transfers energy without transferring matter; light is a transverse electromagnetic wave traveling at 3.0 × 10 8 m/s 3.0 \times 10^8\text{ m/s} 3.0 × 1 0 8 m/s in a vacuum, whereas sound is a longitudinal mechanical wave requiring a physical medium.
Heat transfers spontaneously from higher to lower temperatures through conduction (direct particle contact), convection (fluid bulk movement), or radiation (electromagnetic waves).
Last updated: July 2026
Physical Science: Matter, Energy, Forces & Motion
Physical Science tests your core understanding of how matter behaves, how forces interact with objects to cause motion, and how energy changes form across physical systems.
1. Matter & Phase Transitions
Matter is anything that has mass and takes up space (volume). All matter is composed of basic building blocks called atoms.
Four Fundamental States of Matter
Solid : Fixed volume and fixed shape. Molecules are tightly packed in rigid, fixed positions with minimal kinetic energy.
Liquid : Fixed volume but indefinite shape (takes the shape of its container). Molecules are closely spaced but free to flow past one another.
Gas : Indefinite volume and indefinite shape (expands to fill container completely). Molecules have high kinetic energy and move rapidly in random directions.
Plasma : High-energy ionized gas consisting of free electrons and positively charged ions. Found in stars, lightning bolts, and neon signs.
Phase Transitions
Phase changes are physical changes driven by variations in temperature and pressure. They do not alter the chemical identity of the substance: [Melting] [Evaporation] [Ionization]
- SOLID -------------> LIQUID ---------------> GAS --------------> PLASMA
- <------------- <--------------- <--------------
- [Freezing] [Condensation] [Deionization]
Sublimation : Phase change directly from solid to gas without passing through liquid (e.g., dry ice / solid C O 2 CO_2 C O 2 ).
Deposition : Phase change directly from gas to solid (e.g., frost forming on cold glass).
Endothermic Changes : Absorb heat energy (Melting, Evaporation, Sublimation).
Exothermic Changes : Release heat energy (Freezing, Condensation, Deposition).
2. Classical Mechanics: Forces & Newton's Laws of Motion
A force is a push or pull exerted on an object, measured in Newtons ( N N N ) , where 1 N = 1 kg ⋅ m/s 2 1\text{ N} = 1\text{ kg}\cdot\text{m/s}^2 1 N = 1 kg ⋅ m/s 2 .
Newton's Three Laws of Motion
Law Name Description & Formula
1st Law Law of Inertia An object at rest stays at rest, and an object in motion continues moving at constant velocity unless acted upon by a net external force. (Mass is the measure of inertia).
2nd Law Law of Acceleration The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. Formula: F = m a F = ma F = ma (Force = Mass × \times × Acceleration).
3rd Law Law of Action-Reaction For every action force, there is an equal and opposite reaction force. If object A exerts force on object B, object B exerts an equal force in the opposite direction on object A.
Important Force Concepts
Gravity : Universal attractive force between masses. On Earth, gravitational acceleration ( g g g ) is approximately 9.8 m/s 2 9.8\text{ m/s}^2 9.8 m/s 2 ( 32 ft/s 2 32\text{ ft/s}^2 32 ft/s 2 ).
Weight vs. Mass : Mass is the amount of matter in an object (constant anywhere, measured in kg). Weight is the force of gravity acting on that mass ( W = m g W = mg W = m g , measured in Newtons).
Friction : Force that opposes relative motion between contacting surfaces. Types include static friction (prevents initial movement) and kinetic friction (opposes ongoing sliding motion).
- 3. Work, Power, and Conservation of Energy
- Work and Power Formulas
Work ( W W W ) : Done when a force moves an object across a distance in the direction of the force. W = F × d W = F \times d W = F × d (Work is measured in Joules ( J J J ) , where 1 J = 1 N ⋅ m 1\text{ J} = 1\text{ N}\cdot\text{m} 1 J = 1 N ⋅ m )
Power ( P P P ) : The rate at which work is performed or energy is converted over time. P = W t P = \frac{W}{t} P = t W (Power is measured in Watts ( W W W ) , where 1 Watt = 1 Joule per second 1\text{ Watt} = 1\text{ Joule per second} 1 Watt = 1 Joule per second )
Forms of Energy & Conservation
Kinetic Energy ( K E KE K E ) : Energy of motion possessed by a moving body. K E = 1 2 m v 2 KE = \frac{1}{2} m v^2 K E = 2 1 m v 2
Gravitational Potential Energy ( P E PE PE ) : Stored energy due to an object's position in a gravitational field. P E = m g h PE = m g h PE = m g h
Law of Conservation of Energy : Energy cannot be created or destroyed; it can only transform from one form to another. In a closed system, total mechanical energy remains constant: E total = K E + P E E_{\text{total}} = KE + PE E total = K E + PE .
4. Simple Machines & Mechanical Advantage
Simple machines alter the magnitude or direction of an applied effort force to make work easier, though total work performed remains equal (excluding friction losses).
- Simple Machine Mechanism Real-World Examples
- Lever Rigid bar pivoting on a fixed support point called a fulcrum Crowbar, scissors, see-saw, wheelbarrow
- Pulley Grooved wheel holding a rope or cable to lift loads Flagpole hoist, crane, window blinds
Inclined Plane Slanted flat surface allowing loads to be raised using less force Loading ramp, wheelchair access ramp
- Wheel and Axle Circular wheel attached to a central shaft Steering wheel, door knob, bicycle gears
- Wedge Two inclined planes placed back-to-back used to split objects Axe head, chisel, nail point, knife
- Screw Inclined plane wrapped spirally around a central cylinder Wood screw, jar lid, bottle cap
Mechanical Advantage (MA) : The factor by which a machine multiplies force: MA = Output Force (Load) Input Force (Effort) \text{MA} = \frac{\text{Output Force (Load)}}{\text{Input Force (Effort)}} MA = Input Force (Effort) Output Force (Load) .
5. Waves, Sound & Light
A wave is a disturbance that propagates through space, transferring energy without transferring matter.
Key Wave Parameters
Wavelength ( λ \lambda λ ) : Distance between two consecutive crests or troughs (meters).
Frequency ( f f f ) : Number of complete wave cycles passing a point per second, measured in Hertz ( H z Hz Hz ) .
Amplitude : Height of the wave crest from rest position; corresponds to wave energy/volume.
Wave Velocity Formula : v = f × λ v = f \times \lambda v = f × λ .
Sound vs. Light Comparison
- Feature Sound Waves Light Waves (EM Radiation)
- Type Longitudinal mechanical wave Transverse electromagnetic wave
- Medium Required? Yes (cannot travel in a vacuum) No (travels fastest in a vacuum)
Speed in Vacuum 0 m/s 0\text{ m/s} 0 m/s (No sound in space) 3.0 × 10 8 m/s 3.0 \times 10^8\text{ m/s} 3.0 × 1 0 8 m/s ( 186 , 000 miles/sec 186,000\text{ miles/sec} 186 , 000 miles/sec )
- Speed Trend Fastest in Solids > Liquids > Gases Fastest in Vacuum > Gases > Liquids > Solids
- Pitch / Color Pitch determined by frequency Color determined by frequency/wavelength
- Electromagnetic (EM) Spectrum
Ordered from lowest frequency / longest wavelength to highest frequency / shortest wavelength : Radio Waves → Microwaves → Infrared → Visible Light → Ultraviolet → X-Rays → Gamma Rays \text{Radio Waves} \rightarrow \text{Microwaves} \rightarrow \text{Infrared} \rightarrow \text{Visible Light} \rightarrow \text{Ultraviolet} \rightarrow \text{X-Rays} \rightarrow \text{Gamma Rays} Radio Waves → Microwaves → Infrared → Visible Light → Ultraviolet → X-Rays → Gamma Rays
(Visible light spectrum mnemonic: ROYGBIV — Red, Orange, Yellow, Green, Blue, Indigo, Violet).
6. Thermodynamics & Heat Transfer
Thermal Energy is the total kinetic energy of microscopic particles in a substance. Heat is thermal energy transferred between systems due to a temperature gradient.
Three Mechanisms of Heat Transfer
Conduction : Direct transfer of heat between colliding molecules in physical contact. (Most efficient in dense solids, like a metal spoon heating in soup).
Convection : Thermal transfer through the mass motion of fluids (liquids or gases) caused by density differences. Warm fluid expands, becomes less dense, and rises; cooler fluid sinks.
Radiation : Heat transfer through electromagnetic waves (infrared radiation). Requires no physical medium and can travel across empty space (e.g., sunlight heating Earth).