ASVAB cheat sheet

Cell theory states that all living things are made of cells, cells are the basic unit of life, and new cells arise from existing cells.

Photosynthesis: 6CO2 + 6H2O + light energy -> C6H12O6 + 6O2; this process occurs in chloroplasts and stores energy in glucose.

Atomic number equals the number of protons; mass number equals protons plus neutrons; isotopes have the same protons but different neutrons.

pH scale runs from 0 to 14: below 7 is acidic, 7 is neutral, and above 7 is basic; each unit is a tenfold change in hydrogen-ion concentration.

Igneous rock forms from cooling magma or lava; sedimentary rock forms from compacted or cemented sediments; metamorphic rock forms from heat and pressure.

Water cycle processes include evaporation, condensation, precipitation, runoff, and transpiration.

Arteries carry blood away from the heart; veins carry blood toward the heart; capillaries are thin exchange vessels.

Newton's first law: an object at rest or in uniform motion stays that way unless acted on by a net external force.

Percent: part = percent × whole; convert the percent to a decimal before multiplying.

Percent change = (new value − old value) / old value × 100; a negative result is a decrease.

Average = sum / count; total = average × count.

Distance = rate × time; rate = distance / time; time = distance / rate.

Simple interest: I = P × r × t, where r is the annual rate as a decimal and t is time in years.

Work rates: combined rate = sum of individual rates; time together = 1 / (1/a + 1/b).

Proportion: a/b = c/d implies ad = bc; use matching units on each side.

Mixture problems: amount of solute = concentration × total volume; conserve solute totals when combining solutions.

Prefix pre- means before; post- means after; anti- means against; pro- means for or forward.

Suffix -ology means study of; -ism means practice or doctrine; -able means capable of; -less means without.

Definition context clues often follow a comma, dash, the word or, or the phrase that is.

Contrast clues use but, although, however, or unlike to signal an opposite meaning nearby.

Roots: bene = good, mal = bad, ver = truth, aud = hear, cred = believe, chron = time, bio = life, geo = earth.

Word charge positive, negative, or neutral narrows answer choices when the sentence tone is clear.

Homophones: affect is usually a verb, effect is usually a noun; accept means receive, except means exclude.

Synonyms have similar meanings; antonyms have opposite meanings; eliminate choices that do not match the sentence's logic.

Main idea is the central point about the topic; supporting details explain or prove it, and it is often stated near the beginning or end.

Inference is a conclusion supported by text details but not directly stated; it must stay close to the passage.

Tone is the author's attitude, revealed by word choice, imagery, and sentence structure.

Fact is verifiable with evidence; opinion is a judgment, belief, or feeling and often uses evaluative words.

Sequence clues include first, then, next, finally, before, after, and dates.

Compare/contrast signal words include similarly, unlike, whereas, on the other hand, and both.

Cause/effect signal words include because, due to, therefore, as a result, and consequently.

Author's purpose is commonly to inform, persuade, entertain, or explain; content and language identify the primary purpose.

Slope-intercept form: y = mx + b; slope m = (y2 − y1)/(x2 − x1).

Area: rectangle = lw; triangle = 1/2 bh; circle = πr²; circumference = 2πr.

Volume: rectangular prism = lwh; cylinder = πr²h; sphere = 4/3 πr³.

Pythagorean theorem: a² + b² = c² for a right triangle, where c is the hypotenuse.

Quadratic formula: x = [−b ± √(b² − 4ac)] / (2a) for ax² + bx + c = 0, a ≠ 0.

Exponent rules: x^a x^b = x^(a+b); (x^a)^b = x^(ab); x^0 = 1 for x ≠ 0; x^−a = 1/x^a.

Common conversions: 1/2 = 0.5 = 50%; 1/4 = 0.25 = 25%; 3/4 = 0.75 = 75%.

Mean = sum/count; median = middle value when ordered; mode = most frequent value.

Ohm's law: V = IR; I = V/R; R = V/I.

Power: P = VI; P = I²R; P = V²/R.

Series circuit: R_total = R1 + R2 + ...; current is the same; voltage divides.

Parallel circuit: 1/R_total = 1/R1 + 1/R2 + ...; voltage is the same; current divides.

Resistor color code: black 0, brown 1, red 2, orange 3, yellow 4, green 5, blue 6, violet 7, gray 8, white 9; gold ±5%, silver ±10%.

Capacitor stores energy in an electric field; unit is the farad; it blocks steady DC and passes AC.

Inductor stores energy in a magnetic field; unit is the henry; it opposes changes in current.

AC frequency in the United States is 60 Hz; DC has constant polarity; a diode allows current mainly in one direction.

Digital logic: AND is true only when all inputs are true; OR is true when any input is true; NOT inverts the input.

Four-stroke engine cycle: intake, compression, power, exhaust; the spark plug ignites the compressed air-fuel mixture in a gasoline engine.

Engine oil lubricates, cools, cleans, and seals; check level with the dipstick on a level surface with the engine off.

Battery stores chemical energy; the alternator charges the battery and powers electrical systems while the engine runs.

Hydraulic brakes transmit pressure through fluid; disc brakes use calipers and pads; drum brakes use shoes.

Coolant/antifreeze raises the boiling point and lowers the freezing point; never open a hot radiator.

Tire rotation promotes even wear; alignment adjusts camber, caster, and toe; balancing reduces vibration.

A fuse protects a circuit by melting when current exceeds its rating; replace it with the same rating and never bypass it.

Manual transmission: the clutch disengages the engine from the transmission during gear changes.

Shop safety: disconnect power before repair, use personal protective equipment, and keep flammables away from sparks.

Mechanical advantage = output force / input force; for a lever it also equals effort arm / load arm.

Lever classes: first class has fulcrum between effort and load; second class has load between; third class has effort between.

Pulley: a fixed pulley changes direction but gives no mechanical advantage; a movable pulley has MA = 2; a block and tackle has MA = number of supporting ropes.

Inclined plane MA = length / height; a wedge is a moving inclined plane; a screw is an inclined plane wrapped around a cylinder.

Gear ratio = driven gear teeth / driver gear teeth; a larger driven gear turns slower and delivers more torque.

Pressure = force / area; in a hydraulic press, force ratio equals piston area ratio.

Work = force × distance; power = work / time; the unit of power is the watt.

Efficiency = output work / input work × 100%; it is never greater than 100%.

Torque = force × lever arm distance measured perpendicular to the force.