NG Navy Exam flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Percent change formula

Subtract the original value from the new value, divide the difference by the original value, then multiply by 100. A positive result is an increase; a negative result is a decrease.

Combined work rate

If one worker finishes a job in a hours and another in b hours, together they finish in (a × b) ÷ (a + b) hours, because their individual rates add while times do not.

Simple interest

Interest computed only on the original principal: principal × annual rate × time in years. It never compounds, so the yearly interest amount stays constant.

Weighted average

When groups differ in size, multiply each group's average by its count, add those products, then divide by the total count. A plain average of the averages is wrong.

Quadratic formula

For ax² + bx + c = 0 with a not zero, x equals negative b plus or minus the square root of b squared minus 4ac, all divided by 2a.

Perpendicular slope rule

Two nonvertical lines are perpendicular exactly when their slopes are negative reciprocals, so their product equals negative one. A horizontal line and a vertical line also qualify.

Pythagorean theorem

In a right triangle the square of the hypotenuse equals the sum of the squares of the other two sides: a² + b² = c². It applies only to right triangles.

Interior angle sum

For any polygon with n sides, the interior angles add to (n − 2) × 180 degrees. A triangle therefore totals 180 and a quadrilateral 360 degrees.

Negative exponent rule

A base raised to a negative exponent equals the reciprocal of that base raised to the positive exponent: x to the minus a equals 1 divided by x to the a.

Prefix bene-

A Latin prefix meaning good or well, seen in benevolent (wishing good), benefactor (one who gives help), and beneficial (producing a favorable result).

Root -dict-

A Latin root meaning to say or speak, appearing in dictate (to speak for recording), predict (to say beforehand), and verdict (a stated decision).

Eminent versus imminent

Eminent means famous or outstanding, as in an eminent scientist. Imminent means about to happen soon, as in an imminent storm. Similar spelling, unrelated meaning.

Prefix circum-

A Latin prefix meaning around or about, found in circumference (distance around a circle), circumnavigate (sail around), and circumspect (looking around carefully).

Main idea

The central point an author makes about a topic, broad enough to cover the whole passage. Supporting details illustrate or prove it but cannot replace it.

Valid inference

A conclusion the passage logically requires but does not state outright. It must follow from stated evidence, not from personal opinion or outside knowledge.

Author's tone

The attitude the writer conveys through word choice, such as objective, critical, humorous, or nostalgic. Tone describes the writer, while mood describes the reader's feeling.

Context clue substitution

To answer a vocabulary-in-context question, insert each answer choice into the original sentence and keep only the choice that preserves the passage's meaning.

Newton's second law

The net force on an object equals its mass times its acceleration (F = ma). Doubling the force doubles acceleration; doubling the mass halves it for the same force.

Photosynthesis equation

Six carbon dioxide molecules plus six water molecules, using light energy and chlorophyll, produce one glucose molecule and six oxygen molecules inside chloroplasts.

pH scale

A measure of hydrogen ion concentration: below 7 acidic, 7 neutral, above 7 basic. Each whole step represents a tenfold change in concentration.

Mitochondria function

Organelles that release usable energy by breaking down glucose and storing it as ATP. Cells with high energy demands, such as muscle cells, contain many of them.

Lever mechanical advantage

The effort arm length divided by the resistance arm length. Lengthening the effort arm, or shortening the resistance arm, reduces the force needed to move a load.

Gear ratio

The number of teeth on the driven gear divided by the teeth on the driving gear. A larger driven gear turns slower and with more torque than the driver.

Pascal's principle

Pressure applied to a confined fluid is transmitted undiminished throughout it. In hydraulics, force equals pressure times piston area, so a larger piston lifts more.

Torque balance

A lever is balanced when the clockwise torque equals the counterclockwise torque, where each torque is force multiplied by perpendicular distance from the pivot point.

Ideal mechanical advantage

For an inclined plane, the length of the slope divided by its height. A gentler, longer ramp reduces the force required while increasing the distance moved.

Ohm's law

Voltage equals current times resistance (V = IR). For a fixed resistance, raising voltage increases current proportionally; raising resistance lowers current.

Series circuit rules

One path carries the same current through every component. Resistances add directly, and the supply voltage divides among the components in proportion to resistance.

Parallel circuit rules

Branches share the same voltage while current divides among them. Total resistance is less than the smallest branch, found by adding reciprocals of branch resistances.

Electrical power formulas

Power in watts equals voltage times current, also current squared times resistance, also voltage squared divided by resistance. Any one form works if two quantities are known.

Diode function

A semiconductor device that allows current in one direction only, from anode to cathode. It rectifies alternating current and protects circuits from reversed polarity.

Capacitor behavior

A component that stores charge in an electric field between two plates. It blocks steady direct current while allowing alternating current to pass, and is rated in farads.