ASVAB (Armed Services Vocational Aptitude Battery) flashcards

The ratio of the number of teeth on two meshing gears, which determines the change in speed and torque between them. An inverse relationship exists between teeth count and rotational speed.

• More teeth on the driven gear reduce speed and increase torque.
• Fewer teeth on the driven gear increase speed and reduce torque.
• Formula: N_driver / N_driven = RPM_driven / RPM_driver.

Memory trick: Teeth and Turns: More teeth, less turn speed (but more twisting power).

States that the buoyant force on an object submerged or floating in a fluid is equal to the weight of the fluid displaced by the object.

• Applies to both fully submerged and floating objects.
• Buoyant force acts upwards.
• Explains why objects float or sink.

Memory trick: Archimedes found that displaced water's weight makes things float right.

States that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass (F=ma). It explains how forces cause changes in motion.

• A net force causes acceleration (change in velocity).
• If net force is zero, acceleration is zero (constant velocity or rest).
• Explains why objects start, stop, speed up, slow down, or change direction.

Memory trick: Inertia wants to stay; Force makes it stray; Action-Reaction is the way.

In the absence of non-conservative forces (like friction), the total mechanical energy (potential energy + kinetic energy) of a system remains constant. Gravitational potential energy is converted into kinetic energy, and vice-versa.

• PE_initial + KE_initial = PE_final + KE_final.
• For falling objects: mgh_initial = 0.5mv_final² (if starting from rest).
• Assumes no energy loss to heat, sound, etc.

Memory trick: Energy's never lost, just 'switches' its 'cost' – 'potential' to 'kinetic' it goes.

A net force that acts on an object moving in a circular path and is directed towards the center of the circle. It is essential for maintaining circular motion.

• Always perpendicular to the object's velocity.
• Examples: gravity on satellites, tension in a string swinging a ball.
• Formula: Fc = mv²/r.

Memory trick: Center-seeking force keeps circles neat.

The net force required to keep an object moving in a circular path. For satellites orbiting a planet, this force is provided by the gravitational attraction between the satellite and the planet.

• Always directed towards the center of the circular path.
• Causes a change in direction (acceleration), not speed (if speed is constant).
• Without it, an object in circular motion would fly off tangentially.

Memory trick: Gravity's grip keeps the 'centripetal' curve in the 'orbital' dance.

Systems that use an incompressible fluid to transmit forces from one point to another, often to multiply force or change direction.

• Based on Pascal's Principle.
• Fluid is typically oil.
• Used in brakes, lifts, and heavy machinery.

Memory trick: Fluids Follow Fantastic Fundamental Facts!

In the absence of non-conservative forces (like friction or air resistance), the total mechanical energy (sum of potential and kinetic energy) of a system remains constant.

• PE + KE = Constant.
• Potential energy converts to kinetic energy and vice-versa.
• Often used to solve problems involving objects moving under gravity.

Memory trick: What goes up as potential, comes down as kinetic.

Hydraulic systems use incompressible fluid to transmit pressure, allowing a small force applied to a small piston to generate a larger force on a larger piston, providing mechanical advantage.

• Based on Pascal's Principle (P1 = P2).
• Force is amplified when the output piston area is larger than the input piston area.
• The distance the larger piston moves is proportionally smaller than the smaller piston's travel.

Memory trick: Pascal's Press: Small 'push' on small 'area' means big 'push' on big 'area'.

The ratio of useful work output to the total work input, expressed as a percentage. It indicates how effectively a machine converts input energy into useful output energy.

• Always less than 100% due to friction and other energy losses.
• Calculated as (Work Output / Work Input) * 100%.
• A measure of energy conservation in a system.

Memory trick: Efficient machines produce 'output' from 'input' with minimal 'loss'.

The minimum force required to move an object up an inclined plane, ignoring friction. It is calculated by multiplying the object's weight by the ratio of the ramp's height to its length.

• Provides mechanical advantage by reducing the required force.
• Ideal force = Weight * (Height / Length).
• Actual force is always higher due to friction.

Memory trick: Ramps 'lend' a hand: the 'longer' the ramp, the 'less' force you need for the 'height'.

A twisting force that tends to cause rotation, calculated as the product of force and the perpendicular distance from the pivot to the line of action of the force.

• Torque (τ) = Force (F) × Lever Arm (r)
• Units are typically Newton-meters (Nm) or foot-pounds (ft-lb).
• A longer lever arm increases torque for a given force.

Memory trick: Twist Right, Quit Effortlessly, Use a Longer Spanner!

The pressure exerted by a fluid at rest due to the force of gravity. It increases with depth because the weight of the fluid column above a point increases.

• Increases linearly with depth.
• Depends on fluid density and gravity (P = ρgh).
• Acts equally in all directions at a given depth.

Memory trick: Deeper you dive, more 'weight' of water 'presses' from 'above'.

A mechanical coupling that allows two shafts to rotate at different angles. A single universal joint, when operating at an angle, causes the output shaft to rotate non-uniformly even if the input shaft rotates uniformly.

• Also known as a Cardan joint or Hooke's joint.
• Non-uniformity increases with the angle between shafts.
• Often used in pairs (double Cardan joint) to cancel out non-uniformity.

Memory trick: Angled shafts make the joint 'wobble' the 'ouput speed'.

The theoretical mechanical advantage of a machine, calculated without considering friction or other energy losses. For pulleys, it's the ratio of the distance the effort moves to the distance the load moves.

• IMA = Effort Distance / Load Distance.
• Always greater than or equal to the actual mechanical advantage (AMA).
• For pulley systems, often equal to the number of rope segments supporting the movable pulley(s).

Memory trick: MA: More distance, Less force.

A simple machine consisting of a wheel attached to a smaller axle, both rotating around the same axis. It provides mechanical advantage by applying force to the larger wheel to turn the smaller axle.

• Effort applied to the wheel, load resistance on the axle.
• Mechanical advantage = Radius of Wheel / Radius of Axle.
• Examples: doorknobs, steering wheels, screwdrivers.

Memory trick: LIPS W-W: Lever, Inclined Plane, Pulley, Screw, Wedge, Wheel & Axle.

Pressure is the amount of force applied perpendicular to the surface of an object per unit area over which that force is distributed.

• Formula: P = F / A.
• Units: Pascals (Pa), where 1 Pa = 1 N/m².
• Important in fluid mechanics and structural engineering.

Memory trick: Pressure is Force 'over' Area.

The time taken for a simple pendulum to complete one full oscillation, dependent on its length and the acceleration due to gravity.

• T = 2π√(L/g)
• Period is independent of mass and amplitude (for small angles).
• Increasing length increases period; increasing gravity decreases period.

Memory trick: Lengthy Loops, Gravity Greatly Governs!

Mechanical power is the rate at which work is performed or energy is transferred. It is calculated as work divided by time (P = W/t) or force multiplied by velocity (P = Fv).

• Unit is Watts (Joules per second).
• Work done against gravity is Force × Distance (mgh).
• Higher power means work is done faster.

Memory trick: Power is 'Work' done over 'Time', or 'Force' times 'Velocity'.

Lift is the aerodynamic force that opposes gravity, keeping an aircraft in the air. For a given wing design and angle of attack, lift is directly proportional to the square of the airspeed.

• Generated by airflow over the wings.
• Increases with airspeed, wing area, and angle of attack.
• Must balance weight for level flight.

Memory trick: Thrust pulls, Drag fights, Lift floats, Weight bites.

The ratio of the output force to the input force in a lever system, indicating how much a lever multiplies the applied force.

• Mechanical advantage = Output Force / Input Force
• Mechanical advantage = Distance from fulcrum to effort / Distance from fulcrum to load
• Moving the fulcrum closer to the load increases mechanical advantage.

Memory trick: Levers Make Awesome Gains, Effortlessly!

A type of motion characterized by repetitive back-and-forth movement about a central equilibrium position. It is a periodic motion.

• Examples: pendulum, vibrating string, piston in an engine.
• Often involves conversion between kinetic and potential energy.
• Can be simple harmonic motion if restoring force is proportional to displacement.

Memory trick: Rotate, Translate, Oscillate: The motion states we separate.

The time it takes for a mass attached to a spring to complete one full oscillation. It depends on the mass (m) and the spring constant (k), described by the formula T = 2π√(m/k).

• Period increases with increasing mass.
• Period increases with decreasing spring constant (weaker spring).
• Amplitude of oscillation does not affect the period.

Memory trick: Heavy 'mass' needs 'more time' to 'spring' back.

States that an increase in the speed of a fluid occurs simultaneously with a decrease in static pressure or a decrease in the fluid's potential energy.

• Applies to fluids in motion (liquids and gases).
• Explains how aircraft wings generate lift and how pumps create flow.
• Derived from the principle of conservation of energy.

Memory trick: Fluid's fast flow means pressure's low.

The ideal mechanical advantage of an inclined plane (ramp) is the ratio of the length of the inclined surface to the vertical height it overcomes, assuming no friction.

• Formula: IMA = Length / Height.
• The longer the ramp for a given height, the greater the IMA.
• Allows a smaller force to lift a heavier object over a longer distance.

Memory trick: Ramp's length over height gives MA's might.

The ratio of the number of teeth on the driven gear to the number of teeth on the driving gear, which determines the change in speed and torque.

• Gear Ratio = (Number of teeth on driven gear) / (Number of teeth on driving gear)
• Speed Ratio = (RPM of driving gear) / (RPM of driven gear)
• Gear ratio is inversely proportional to speed ratio.

Memory trick: Teeth Tell The Turning Times!

Successive fractional spending involves calculating expenditures where subsequent fractions are applied to the *reduced* or remaining amount after previous expenditures.

• Each spending calculation uses the current remaining balance as its 'whole'.
• Often involves finding the fraction remaining after each step.
• Requires careful tracking of the current balance.

Memory trick: Imagine a wallet with money spent, then more spent from what's left.

In inverse proportion problems involving work, the product of the number of workers and the time taken to complete a task remains constant, assuming all workers operate at the same rate.

• More workers mean less time to complete the same amount of work.
• Formula: Worker1 × Time1 = Worker2 × Time2.
• Used to find an unknown worker count or time.

Memory trick: More hands make light work, so time goes down.

Unit rate and conversion involves determining a rate per single unit of time or quantity, and then converting the total calculated amount into a different unit of measure.

• Unit rate: amount / time (or quantity).
• Requires consistent units for rate calculation.
• Conversion factors are essential for changing units (e.g., MB to GB, minutes to hours).

Memory trick: Find how much you get per minute, then multiply for the total time, then change the label.

Fractional decrease involves calculating a reduction where the amount removed is a fraction of a *current* fractional quantity, then finding the resulting fraction of the original whole.

• The 'of' in '1/3 of the fuel' means multiplication.
• The reduction applies to the *current* amount, not always the original total.
• Final answer must be in relation to the *original* whole.

Memory trick: Cutting a slice from a partially eaten pie.

The amount of additional load or volume an object can hold before reaching its maximum limit.

• Calculated by subtracting the current amount from the maximum capacity.
• Often used in logistics and transport to determine available space or weight allowance.

Memory trick: Capacity is like a cup, how much more can it sup?

Determining the duration of a journey or process given the distance covered and the rate of travel (speed).

• Formula: Time = Distance / Rate (Speed).
• Units must be consistent (e.g., miles and miles per hour).

Memory trick: Time is distance over speed, a journey's true deed.

Remaining distance time involves calculating the time required to complete the unfinished portion of a journey, given the remaining distance and a constant speed.

• First, find the remaining distance.
• Use the formula Time = Distance / Speed.
• Convert time units as necessary (e.g., hours to minutes).

Memory trick: How long until you reach the finish line from where you are, at your current speed?

Determining the number of days a supply will last given a starting quantity and a daily consumption rate.

• Calculated by dividing total quantity by daily rate.
• Any resupply information is a distractor if the question specifies 'no resupply'.

Memory trick: Total in the tank, daily drain, how long till the last rain?

Solving a problem that involves calculating a total quantity, a consumption rate, and then determining duration.

• Requires multiple arithmetic operations.
• Often involves multiplication to find total, and division to find duration or rate.

Memory trick: Total stock, daily need, then how long indeed!

Unit conversion and division involves changing a quantity from one unit to another, then distributing it equally among a given number of entities.

• Requires knowledge of conversion factors (e.g., 1 ton = 2,000 pounds).
• Order of operations matters: convert then divide, or vice versa if applicable.
• Ensures consistent units for accurate calculation.

Memory trick: Imagine dividing a giant candy bar after breaking it into smaller pieces.

Adding time in 24-hour format involves summing hours and minutes separately, remembering that minutes 'roll over' at 60, adding to the hours.

• Minutes are base 60, hours are base 24.
• No AM/PM distinction in 24-hour time.
• Carry over minutes exceeding 59 to the hour count.

Memory trick: Think of a clock's hands moving forward, but minutes jump to hours at 60.

The process of dividing a total quantity into identical portions among a given number of recipients.

• Achieved through division.
• Ensures fairness and equal share for all parties.

Memory trick: Divide and conquer, each gets a piece to ponder.

Division is used to determine how many equal groups can be made from a total quantity or to find the size of each group.

• Total quantity is divided by the size of each group.
• Result is the number of groups.
• Essential for resource allocation and packing.

Memory trick: Divide the 'Big Total' by the 'Small Group' to get 'How Many Groups'.

Reserve fuel calculation involves determining an additional amount of fuel, typically a percentage of the primary fuel requirement, to ensure safety margins or contingency for a mission.

• Reserve is usually a percentage of the *required* fuel.
• Total fuel = Required Fuel + Reserve Fuel.
• Crucial for aviation safety and mission planning.

Memory trick: Think of packing an extra snack, just in case, on top of your planned meal.

Calculating a fraction of a whole involves multiplying the fraction by the total quantity to find a specific part.

• The 'whole' is the total amount.
• The fraction represents a part of that total.
• To find the part, multiply the fraction by the whole.

Memory trick: Think of cutting a pizza into slices and giving some away.

Fractional time calculation involves determining the total time required for a task when a known fraction of the task has been completed in a given amount of time.

• Uses the concept of direct proportion.
• If a fraction 'part/whole' takes 'X' time, then '1/whole' takes 'X/part' time.
• Total time is (X/part) * whole.

Memory trick: If you know how long a piece of the pie takes, you can find the whole pie's time.

A long, non-ratcheting bar used with sockets to apply high torque to loosen stubborn fasteners.

• Provides maximum leverage for loosening.
• Does not have a ratcheting mechanism.
• Used when a standard ratchet cannot provide enough force.

Memory trick: Leverage is the key to turning the unmovable.

The critical steps taken before applying heat and solder to ensure a clean, strong, and leak-free joint.

• Cleanliness is paramount for solder adhesion.
• Oxidation prevents proper bonding.
• Deburring removes sharp edges that impede flow.

Memory trick: Clean copper craves contact.

The procedure to accurately determine the amount of engine oil in the crankcase using the dipstick.

• Vehicle must be on level ground.
• Engine should be warm but off for 5-10 minutes.
• Wipe dipstick clean, reinsert, then check.

Memory trick: Run, rest, then read right.

The reduction in electrical potential energy (voltage) as current flows through a component due to its resistance.

• A working component will have a voltage drop.
• 0V drop means component is acting as a short or a closed switch.
• Full battery voltage drop means component is open or disconnected.

Memory trick: Voltage drops when work is done; 0V means current's free run.

The method of using a hacksaw to efficiently cut metal, focusing on proper pressure application and stroke direction.

• Cuts on the push stroke.
• Relieve pressure on the pull stroke.
• Use long, steady strokes for efficiency.

Memory trick: Push to cut, pull to clear, make your metal fears disappear.

A high-pitched noise caused by the serpentine belt slipping on one or more pulleys.

• Commonly due to insufficient tension or worn belt.
• Worsens with high accessory load (e.g., A/C, power steering).
• Can also be caused by misaligned pulleys or contaminated belt.

Memory trick: Slipping belt sings a sad song.

A common drill bit type with helical flutes, used for general-purpose drilling in various materials including metal, wood, and plastic.

• Most versatile and widely used drill bit.
• Comes in different materials (HSS, Cobalt, Carbide).
• Requires lubrication and slower speeds for metal.

Memory trick: Each bit has its job, a twist for metal's tough knob.

The process of machining a brake rotor's surface to remove imperfections like scoring, warpage, or rust, providing a smooth surface for new pads.

• Done if rotor thickness is above minimum specification.
• Removes grooves and ensures flatness.
• Always done in conjunction with new brake pads.

Memory trick: Pads and rotors work as a pair, neglect one and safety's rare.

The tendency of a circular saw blade to tear wood fibers on the top surface of the workpiece as it cuts upwards.

• Blade teeth cut upwards.
• Splintering occurs on the top surface.
• Place good side up to reduce visible splintering.

Memory trick: Circular saws 'climb' up, so the good side goes high.

The tire pressure measured when the vehicle has been stationary for at least three hours or has not been driven for more than a mile.

• Always check tire pressure when tires are cold.
• Warm tires will show a higher pressure reading.
• Adjust pressure to manufacturer's cold PSI specification.

Memory trick: Cold tires tell the true story, warm ones rise like a hot air balloon.

A circuit in which components are connected end-to-end, forming a single path for current flow.

• Current is the same through all components.
• Total resistance is the sum of individual resistances (R_total = R1 + R2 + ...).
• Total voltage is the sum of individual voltage drops (V_total = V1 + V2 + ...).

Memory trick: Series: Same Current, Summed Resistance, Split Voltage.

An electronic signal that represents data as a sequence of discrete values, typically binary (0s and 1s), rather than continuous values.

• Uses discrete, distinct values.
• Often represented by two states (high/low, on/off).
• Less susceptible to noise degradation over long distances than analog signals.

Memory trick: Digital Differentiates, Analog Ambles.

The specific frequency at which an inductor (L) and a capacitor (C) in an LC circuit achieve maximum energy transfer, calculated by f = 1 / (2π√(LC)).

• Determines the natural oscillation frequency of the circuit.
• Used in tuning circuits for radios and filters.
• Dependent on both inductance (L) and capacitance (C).

Memory trick: Frequency Finds Fun with Fancy LC.

An inductor is a passive electrical component that stores energy in a magnetic field when electric current flows through it, and its primary function is to oppose changes in current.

• Opposes changes in current flow.
• Stores energy in a magnetic field.
• Measured in Henries (H).

Memory trick: Inductors Insist on Inertia of Current.

A semiconductor device made from silicon that allows current to flow primarily in one direction, characterized by a forward voltage drop of approximately 0.7V.

• Made from silicon semiconductor material.
• Allows current flow in one direction (forward bias).
• Requires approximately 0.7V to turn on (forward voltage drop).

Memory trick: Diode's Direction Determines Drop.

An electrical circuit consisting of an inductor (L) and a capacitor (C) that resonates at a specific frequency.

• Resonant frequency (f) is where inductive reactance equals capacitive reactance.
• Formula: f = 1 / (2π√(LC)).
• Used in tuning circuits, filters, and oscillators.

Memory trick: Resonance: 2 Pi Radian Frequency, Root of LC.

A three-terminal semiconductor device that can conduct current in either direction when triggered, commonly used for AC power control applications like light dimmers and motor speed controls.

• Bidirectional current flow (controls AC).
• Has a gate terminal for triggering.
• Often seen as two SCRs in inverse parallel.

Memory trick: Triac Twists Two-way Triggering.

A capacitor used in power supply circuits to reduce ripple voltage, converting pulsating DC from a rectifier into a smoother, more stable DC output.

• Placed after the rectifier.
• Charges during voltage peaks, discharges during valleys.
• Reduces ripple, provides smoother DC.

Memory trick: Capacitor Creates Calm Current.