ASVAB · Cheat Sheet
Line score subtests (not AFQT):
Study Priority: After AFQT (WK, PC, AR, MK) is secured.
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| Domain | High-Yield Topics | |
| Life Science (~50%) | Cells, body systems, photosynthesis, genetics, ecology | |
|---|---|---|
| Physical Science (~50%) | Newton's laws, energy, waves, thermodynamics, chemistry basics | |
| Formula | Use | |
| V = IR | Voltage given current & resistance | |
| I = V/R | Current when voltage ↑ → current ↑ | |
| R = V/I | Resistance inversely proportional to current | |
| Property | Series | Parallel |
| Voltage | Divides across components | Same across all branches |
| Current | Same through all | Divides at branches |
| Resistance | Adds: R_total = R₁ + R₂ + ... | Reciprocal: 1/R_total = 1/R₁ + 1/R₂ + ... |
| Total R | Always greater than largest R | Always less than smallest R |
| Machine | MA Formula | Key Principle |
| Lever | MA = effort arm / load arm | Longer lever arm = more advantage |
| Pulley | MA = # of supporting ropes | Each rope shares the load |
| Inclined Plane | MA = length / height | Longer slope = easier (less force, more distance) |
| Gear | MA = input teeth / output teeth | Large gear in = small gear out spins faster |
| Hydraulics | P = F/A (pressure) | Pressure equal everywhere; large piston moves small distance |
| Concept | Rule | |
| Friction | Opposes motion; kinetic < static | |
| Momentum | p = m × v; greater speed or mass = harder to stop | |
| Torque | τ = F × distance from pivot; perpendicular force matters | |
| Equilibrium | ΣF = 0 and Στ = 0; object not accelerating | |
| Newton's 1st Law | Object in motion stays in motion (unless force applied) | |
| Newton's 2nd Law | F = ma; more mass or acceleration = more force | |
| Newton's 3rd Law | Action-reaction: forces equal & opposite | |
| Stroke | What Happens | |
| 1. Intake | Intake valve opens; piston down; fuel-air mixture in | |
| 2. Compression | Both valves closed; piston up; mixture compressed | |
| 3. Power | Spark plug fires; explosion pushes piston down (only power stroke) | |
| 4. Exhaust | Exhaust valve opens; piston up; burnt gases expelled | |
| System | Function | Common Failure |
| Alternator | Generates electricity while engine runs | Charges battery |
| Battery | Stores electrical energy | Starts engine only |
| Spark Plug | Ignites fuel-air mixture | Timing = power |
| Transmission | Transfers power to wheels; changes gear ratios | Manual vs. automatic |
| Radiator | Cools engine via coolant circulation | Overheating if blocked |
| Brakes | Friction pads slow wheels | Hydraulic system (fluid pressure) |
| Tool | Measures / Does | Key Detail |
| Micrometer | Precise measurements (0.01 mm) | More accurate than calipers |
| Calipers | Inner/outer diameter | Vernier calipers for precision |
| Torque Wrench | Applies exact tightening force (lb-ft or N·m) | Only tool for spec fastening |
| Drill Press | Holes perpendicular to surface | Cleaner than hand drill |
| File | Smooths metal/wood edges | Stroke direction matters |
| Fastener | Use | Property |
| Bolt + Nut | Heavy load; removable | Through-hole required |
Aligned to the official ASVAB technical manual.
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