Your FREE Mechanical Aptitude Flashcards 2026 – 200+ Cards

The factor by which a simple machine multiplies your input force — output force ÷ input force. A machine never gives free work: force saved is paid back in distance.

A pulley anchored in place. It only changes the direction of the force (pull down to raise up) and has a mechanical advantage of 1 — you still pull the full weight.

A pulley that travels with the load on two rope strands, so each strand carries half. Mechanical advantage of 2 — you pull half the weight but twice the rope.

A system of fixed and movable pulleys. Its mechanical advantage equals the number of rope strands directly supporting the movable block.

Count the rope strands that support the load; that number is the mechanical advantage. Effort = load ÷ number of supporting strands.

A rigid bar that pivots on a fulcrum. Effort × effort-arm = load × load-arm, so a longer effort arm multiplies your force.

The fixed pivot point a lever turns on.

Effort × effort-arm = load × load-arm. To balance a lever, the weight-times-distance must be equal on both sides of the fulcrum.

Fulcrum in the middle, between effort and load. Examples: crowbar, seesaw, scissors, pliers. Can multiply force or just change direction.

Load in the middle, between fulcrum and effort. Always multiplies force (MA > 1). Examples: wheelbarrow, nutcracker, bottle opener.

Effort in the middle, between fulcrum and load. Trades force for speed and range (MA < 1). Examples: tweezers, fishing rod, the human forearm.

Effort arm length ÷ load arm length. A 24-inch effort arm over a 6-inch load arm gives a mechanical advantage of 4.

The driven gear's teeth divided by the driver gear's teeth. A higher ratio means the driven gear turns slower with more torque.

Two externally meshed gears always turn in opposite directions — if one turns clockwise, the other turns counterclockwise.

A gear placed between the driver and driven gear. It reverses the direction of rotation but does NOT change the overall gear ratio.

The larger gear turns slower but with more torque; the smaller gear turns faster with less torque.

An open (uncrossed) belt makes both pulleys turn the same direction; a crossed (figure-eight) belt reverses the driven pulley. The smaller pulley turns faster.

A simple machine in which a large wheel turns a smaller axle (or vice versa). Mechanical advantage = wheel radius ÷ axle radius.

A ramp that reduces the force to raise a load by spreading the work over a longer distance. Mechanical advantage = slope length ÷ vertical height.

A moving inclined plane (two ramps back to back). It converts a forward push into a strong sideways splitting or gripping force. Example: an axe, a doorstop.

An inclined plane wrapped around a cylinder. Its pitch is the distance it advances along its axis in one full turn.

A worm gear meshing a toothed wheel. It produces a large speed reduction and often self-locks, resisting being driven backward.

A basic device that changes the size or direction of a force to make work easier. The six classic types are the lever, pulley, wheel and axle, inclined plane, wedge, and screw.

Seesaw, crowbar, scissors, pliers, and a claw hammer pulling a nail — all have the fulcrum sitting between the effort and the load.

Wheelbarrow, bottle opener, nutcracker, and a hand-truck dolly — the load sits between the fulcrum and the effort, always giving a mechanical advantage greater than 1.

Tweezers, tongs, a broom, a fishing rod, and the human forearm — the effort is applied between the fulcrum and the load, trading force for greater speed and range of motion.

The distance from the fulcrum to the point where the effort (input force) is applied on a lever. A longer effort arm gives more mechanical advantage.

The distance from the fulcrum to the load (resistance) on a lever. A shorter load arm relative to the effort arm increases mechanical advantage.

A lighter person sits farther from the pivot and a heavier person sits closer, so that weight × distance is equal on both sides of the fulcrum.

A pulley system combining fixed and movable pulleys to multiply force. Mechanical advantage equals the number of rope sections supporting the load.

One fixed pulley to change direction plus one movable pulley to share the load. Two supporting strands give a mechanical advantage of 2, halving the effort.

A pulley with a mechanical advantage of 4 cuts your pulling force to one-quarter, but you must pull four times as much rope to raise the load the same height.

MA = ramp length ÷ vertical height. A 12-foot ramp rising 3 feet has a mechanical advantage of 4, so the push needed is one-quarter of the load's weight.

A longer, gentler ramp reduces the force needed to raise a load, but the load must travel a greater distance — the same total work is spread out.

The distance a screw advances in one full turn. A finer pitch (threads closer together) gives more mechanical advantage but requires more turns.

Threads spaced closer together let a screw move less per turn, multiplying force more — like a tighter inclined plane wrapped around the shaft.

MA = length of the slope ÷ width of the thick end. A long, thin wedge splits with far more force than a short, fat one.

The large steering wheel turns a thin steering column, multiplying the driver's force. The bigger the wheel relative to the axle, the greater the mechanical advantage.

The wide knob is the wheel and the latch spindle is the axle. Turning the large knob produces enough force to turn the small spindle and retract the latch.

A series of meshed gears that transmits motion and torque. Each external mesh reverses rotation direction, and the overall ratio depends only on the first and last gears.

The gear connected to the power source that drives the rest of the train. Its tooth count compared to the driven gear sets the gear ratio.

The output gear turned by the driver. A larger driven gear turns slower with more torque; a smaller driven gear turns faster with less torque.

A small gear driving a large gear reduces output speed but increases torque — useful for heavy lifting or slow, powerful motion.

A large gear driving a small gear raises output speed but lowers torque — useful where fast rotation matters more than force.

A 12-tooth driver turning a 36-tooth driven gear gives a 3:1 ratio: the big gear turns one-third as fast but with three times the torque.

Gears with angled teeth that transmit rotation between shafts meeting at an angle, usually 90 degrees — as in a hand drill or a car's differential.

A round pinion gear meshing a flat toothed bar (the rack). It converts rotation into straight-line motion, as in steering systems.

A chain links two toothed sprockets so they always turn the same direction. The smaller sprocket spins faster, like the gears on a bicycle.

On a belt drive, the larger pulley turns slower than the smaller one. Speed is inversely proportional to pulley diameter.

A rotating oval or lobed part that pushes a follower up and down, converting rotary motion into repeated linear motion — as in an engine's valve lifters.

A linkage that turns rotary motion into back-and-forth straight-line motion, like the crankshaft and piston in an engine.

A toothed wheel and a catch that lets motion go one way only and locks against the other — found in winches, socket wrenches, and tie-down straps.

Useful output work ÷ input work, always less than 100% because friction wastes some energy as heat. No real machine is perfectly efficient.

A machine cannot create energy. What you gain in force you give back in distance, so input work always equals output work plus friction losses.

The distance the effort moves divided by the distance the load moves. For an ideal machine it equals the mechanical advantage.

A screw geared to lift heavy loads, like a car jack. Its fine thread pitch gives huge mechanical advantage, turning a small crank force into a large lift.

A longer lug wrench applies more torque to a bolt for the same hand force, because torque equals force times the distance from the pivot.

A first-class lever used to lift or move heavy objects. A longer bar and a closer fulcrum to the load both increase the lifting force.

A turning or twisting force, equal to the applied force times the distance from the pivot (the lever arm). A longer wrench makes more torque for the same push.

An object's resistance to a change in its motion. It increases with mass, so a heavier object is harder to start, stop, or turn.

An object stays at rest, or keeps moving in a straight line at constant speed, unless an unbalanced (net) outside force acts on it. The law of inertia.

The inward force that holds an object on a circular path, pointing toward the center. Remove it and the object flies off straight along the tangent.

The apparent outward shove felt in a turn. It is really inertia resisting the change in direction, not a real outward force.

Splitting one angled force into two perpendicular parts — a horizontal component and a vertical component — that together produce the same effect.

When two forces act at an angle, they add as vectors into one resultant that points between them and can exceed either single force.

A resisting force that acts opposite to the direction of motion (or attempted motion) between surfaces in contact.

A heavy spinning wheel that stores rotational energy. Its rotational inertia smooths out an engine's speed fluctuations between power strokes.

A weight added to a crane or elevator to balance the load, so the motor or operator only has to move the difference, reducing required force.

The acceleration of an object equals the net force divided by its mass: a = F ÷ m. More force gives more acceleration; more mass gives less.

For every action there is an equal and opposite reaction. Forces always come in pairs acting on two different objects.

A push or pull that can start, stop, speed up, slow down, or change the direction of motion. Measured in pounds or newtons.

The single force left after adding all forces on an object. If it is zero the object stays at rest or moves at constant velocity; if not, the object accelerates.

Forces that cancel out to a net force of zero. The object's motion does not change — it stays still or keeps moving steadily.

Forces that do not cancel, leaving a net force. They cause an object to accelerate in the direction of the net force.

The state in which all forces and all torques on an object are balanced, so it neither accelerates nor rotates.

The resisting force that keeps a stationary object from sliding. It rises to match the push until the object finally breaks free and moves.

The friction between surfaces already sliding past each other. It is usually a bit less than the static friction needed to start the motion.

The small resistance a wheel or ball meets as it rolls. It is far less than sliding friction, which is why wheels and bearings ease motion.

Lubricants, smoother surfaces, wheels, rollers, and ball bearings all cut friction, letting machines run easier and waste less energy as heat.

Friction increases when an object presses harder on a surface, so a heavier load is harder to slide. It does not depend much on contact area.

An object's mass times its velocity. A heavy or fast-moving object has large momentum and is hard to stop or deflect.

In a collision with no outside forces, the total momentum before equals the total momentum after — momentum is transferred, not lost.

A force applied over a time interval that changes momentum. A longer contact time, as in airbags, lowers the peak force during a stop.

The force a spring exerts is proportional to how far it is stretched or compressed: F = k × x. Stretch it twice as far and it pulls back twice as hard.

The stiffness rating (k) of a spring — the force needed per unit of stretch. A high spring constant means a stiff, hard-to-deform spring.

The rate at which velocity changes over time. Speeding up, slowing down, or turning all count as acceleration because velocity includes direction.

Speed in a given direction. Two objects at the same speed but heading different ways have different velocities.

How fast an object moves, found as distance traveled ÷ time taken. It has size but no direction.

Mass is the amount of matter in an object and never changes; weight is the pull of gravity on that mass and varies with location, such as on the Moon.

When you push on a wall, the wall pushes back on you with equal force. A rocket pushes gas down and the gas pushes the rocket up.

Whatever keeps an object curving — tension in a string, friction on tires, or gravity on a satellite — all pull inward toward the center of the circle.

A longer wrench produces more torque for the same hand force, because torque = force × lever-arm length. Doubling the length doubles the turning effect.

The combined turning effect of all torques on an object. When clockwise and counterclockwise torques are equal, the object does not rotate.

The pulling force carried along a rope, cable, or chain. It is the same throughout an ideal rope and acts away from the object at each end.

A squeezing force that pushes the ends of an object toward each other, as a column carries the weight pressing down on it.

The support force a surface pushes back with, perpendicular to the surface. It balances the part of an object's weight pressing into the surface.

Motion under gravity alone, with no air resistance. Every object accelerates downward at the same rate regardless of weight.

The curved path of a thrown object. Its horizontal motion stays steady while gravity pulls it down, producing an arc.

A weight swinging on a string or rod. Its swing time depends on length, not on the weight — a longer pendulum swings more slowly.

Pushing a swing in time with its natural rhythm makes it swing higher. Matching a force to an object's natural frequency builds large vibrations.

The backward force air exerts on a moving object. It grows with speed and with frontal area, which is why streamlined shapes move easier.

The perpendicular distance from a pivot to the line of an applied force. The longer it is, the more torque that force produces.

In stable equilibrium an object returns to its position after a small nudge; in unstable equilibrium a small nudge makes it tip or roll away.

Tilting a road or track inward lets part of the surface's push supply centripetal force, helping vehicles turn without relying only on tire friction.

The attractive force pulling objects toward Earth's center, giving weight and an acceleration of about 9.8 meters per second squared near the surface.

Any push or pull a person or machine directly exerts on an object, such as pushing a cart or pulling a rope.

For the same force, a heavier object accelerates less than a lighter one because acceleration equals force divided by mass.

Pressure applied to a confined fluid is transmitted equally and undiminished in all directions throughout the fluid.

Force per unit area: P = F ÷ A. The same force over a smaller area gives a higher pressure.

Force = pressure × area. A larger output piston area produces a larger force at the same pressure — how a hydraulic jack multiplies force.

Output piston area ÷ input piston area. A 6-times-larger output piston multiplies the input force by 6.

Fluid pressure increases with depth because the deeper fluid supports the weight of all the fluid above it. It depends on depth, not on the tank's width.

The upward force a fluid exerts on a submerged object, equal to the weight of the fluid the object displaces (Archimedes' principle).

If buoyant force > weight, the object floats; if buoyant force < weight, it sinks; if they are equal, it stays suspended at depth.

Its hollow shape displaces enough water for the buoyant force to equal its weight, while a solid steel block displaces too little water and sinks.

Squeezing a confined liquid barely changes its volume — which is exactly why hydraulic systems transmit pressure instead of just squashing down.

A valve that lets fluid flow in only one direction and blocks backflow. Forward pressure opens it; reverse pressure seats it shut.

The use of confined liquids to transmit and multiply force. Because liquids barely compress, pressure applied at one piston appears fully at another.

A device where a small force on a small piston creates pressure that acts on a large piston, producing a much larger output force.

The large output piston of a hydraulic system makes more force but moves a shorter distance, so the small input piston must travel much farther.

An object in a fluid is pushed up by a buoyant force equal to the weight of the fluid it displaces.

The volume of fluid pushed aside by a submerged object. More displaced fluid means a greater buoyant force lifting the object.

In a moving fluid, faster flow means lower pressure. Fast air over a curved wing lowers the pressure on top and helps create lift.

When fluid speeds up through a narrowed pipe, its pressure drops. This pressure dip is used in carburetors and spray nozzles.

The weight of the air column pressing on everything at Earth's surface, about 14.7 pounds per square inch at sea level.

A tube that carries liquid up over a barrier and down to a lower level. Once started, the heavier downward column keeps the flow going by itself.

A pump that lowers pressure above a liquid so atmospheric pressure pushes the liquid up the pipe. It can lift water only about 34 feet at most.

A pump that pushes liquid up with a piston instead of relying on suction, letting it move fluid to far greater heights than a suction pump can.

Mass per unit volume. An object less dense than a fluid floats in it; an object more dense sinks.

The ratio of a material's density to water's density. A value below 1 means it floats on water; above 1 means it sinks.

P = F ÷ A. A sharp knife or a thin heel concentrates force on a tiny area, producing very high pressure.

A confined fluid pushes equally on every wall of its container, not just downward — pressure acts in all directions at a given depth.

Pressure measured above atmospheric pressure, the way a tire gauge reads. Absolute pressure adds the surrounding atmospheric pressure to it.

Using pressurized air to transmit force or do work. Unlike liquids, air compresses, so pneumatic systems are springier than hydraulic ones.

For a steady flow, narrowing a pipe makes the fluid speed up and widening it slows the fluid down, since the same volume must pass each second.

A fluid's resistance to flowing. Honey is highly viscous and pours slowly; water has low viscosity and flows freely.

The pull along a liquid's surface that makes it act like a stretched skin, letting small insects rest on water and droplets bead up.

The pressure a still fluid exerts due to gravity. It grows with depth and with the fluid's density, independent of the container's shape.

A valve that opens to release fluid when pressure climbs too high, protecting tanks and pipes from bursting.

A water tower stores water high up so gravity creates pressure throughout the system. The higher the tank, the greater the water pressure below.

The marking on a ship's hull showing the safe loading depth. A heavier load makes the ship ride lower until buoyancy again balances the weight.

Water expands and becomes less dense when it freezes, so ice is lighter than the liquid water it displaces and floats on top.

Gravity gives every object the same downward acceleration regardless of mass, so without air resistance a heavy and a light object fall and land together.

The steady falling speed reached when air resistance grows to balance gravity; net force is then zero and the object stops accelerating.

An object thrown straight up has zero velocity at its highest point, even though gravity still acts on it and pulls it back down.

Heat transfer through direct contact, as a metal spoon's handle warms in hot soup. Metals conduct heat well; foam and air are poor conductors.

Heat carried in a moving fluid: warm, less-dense fluid rises and cooler, denser fluid sinks, circulating heat through air or water.

Heat carried as infrared energy through space without a medium, as a campfire warms your skin from across a yard.

A material that slows heat flow, such as foam or trapped air. It keeps coffee warm by resisting conduction.

Most materials expand when heated and contract when cooled — why gaps are left in steel rail and a hot lid loosens on a glass jar.

A conductor (copper) lets current flow with little resistance; an insulator (rubber, plastic) resists current flow and prevents shocks.

A circuit with one current path. If one bulb burns out, the circuit breaks and every bulb goes dark.

A circuit where each branch has its own path. If one bulb fails, the others keep working.

A safety device that melts and breaks a circuit when the current gets too high, cutting power before the wiring overheats.

The single point where an object's weight can be treated as acting. An object balances when supported directly under it.

An object stays upright while its center of gravity is above its base of support; it tips when the center of gravity passes beyond the base's edge.

The most stable arrangement. Race cars ride low and tractors use a wide wheelbase to resist tipping.

Force applied through a distance: W = force × distance. No distance moved means no work done, no matter how hard you push.

The rate of doing work: power = work ÷ time. Doing the same work faster requires more power.

The capacity to do work. It comes in forms like kinetic, potential, heat, and electrical, and can change form but is never destroyed.

The energy of a moving object, equal to one-half mass times velocity squared. Doubling the speed quadruples the kinetic energy.

Stored energy due to position or condition, such as a raised weight or a stretched spring, ready to be released as motion.

The energy an object has from its height: PE = weight × height. Lifting a load higher stores more energy in it.

Energy is never created or destroyed, only changed from one form to another. A falling object turns potential energy into kinetic energy.

At the top of its swing a pendulum has maximum potential energy and zero motion; at the bottom it has maximum kinetic energy and least height.

A unit of power equal to 550 foot-pounds of work per second, or about 746 watts. It rates how fast an engine or motor can do work.

Voltage = current × resistance, or V = I × R. For a fixed voltage, higher resistance means lower current.

The electrical pressure that pushes current through a circuit, measured in volts. It is the driving force behind the flow of electrons.

The flow of electric charge through a conductor, measured in amperes. More voltage or less resistance increases the current.

The opposition to current flow, measured in ohms. Thin or long wires and poor conductors have higher resistance.

In a series circuit, resistances add up, so total resistance rises and the same current flows through every component.

In a parallel circuit, each branch gets the full voltage and current splits among the branches, so total resistance is lower than any one branch.

Power = voltage × current (P = V × I). A device drawing more current at a given voltage uses more power, measured in watts.

A device that stores chemical energy and converts it into electrical energy, providing the voltage that drives current through a circuit.

A resettable switch that trips open when current is too high, protecting wiring. Unlike a fuse, it can be switched back on after the fault clears.

An unintended low-resistance path that lets a large current flow, which can overheat wires and trip a breaker or blow a fuse.

Connecting a device to the earth or a common return so stray current flows safely away instead of through a person, preventing shocks.

The force from magnets and moving charges. Like poles repel, opposite poles attract, and every magnet has both a north and a south pole.

The two ends of a magnet where its force is strongest. North attracts south, but two norths or two souths push apart.

A coil of wire that becomes magnetic when current flows through it. More turns or more current makes it stronger, and cutting the power turns it off.

A device that turns electrical energy into rotating motion using the force between magnetic fields and current-carrying coils.

A device that turns motion into electricity by spinning a coil within a magnetic field, the reverse of a motor.

A device that raises or lowers AC voltage using two coils. More turns on the output coil raise voltage; fewer turns lower it.

Electric current that flows steadily in one direction, as supplied by batteries.

Electric current that reverses direction many times each second, the form delivered by household wall outlets.

A device that opens or closes a circuit. An open switch breaks the path and stops current; a closed switch completes it and lets current flow.

Temperature measures how hot something is; heat is the energy that flows from a hotter object to a cooler one until they reach the same temperature.

A material that lets heat pass through easily, such as metal. It feels cold to the touch because it quickly draws heat from your hand.

Two bonded metals that expand at different rates, bending when heated. It is used in thermostats to open or close a circuit at a set temperature.

A deliberate gap left in bridges, rails, and pipes so the material can expand in heat and contract in cold without buckling or cracking.

Rubbing surfaces converts mechanical energy into heat, which is why brakes warm up and why machines need lubrication to limit heat buildup.

A faster vehicle carries far more kinetic energy, so it needs a much longer distance to stop, because energy rises with the square of speed.

A compressed or stretched spring holds elastic potential energy that is released as motion when the spring returns to its natural shape.

Heat always flows naturally from a warmer object to a cooler one, never the other way without help such as a refrigerator.

A machine cannot output more energy than it takes in; some input energy always becomes waste heat, so efficiency is always below 100%.

A lever multiplies force but not work — the effort end moves a longer distance so that effort × its distance equals load × its shorter distance.

The unit of power equal to one joule of work per second. A 100-watt bulb uses energy at twice the rate of a 50-watt bulb.

The standard unit of work and energy, equal to one newton of force acting through one meter.

A conductor wrapped in a non-conducting cover like rubber or plastic, so current stays in the wire and does not shock or short to other wires.

A build-up of electric charge on a surface, often from rubbing, that can jump as a spark when it finds a path to discharge.

A unit of electrical energy equal to one watt of power used for one hour. Power companies bill in kilowatt-hours, a thousand of these.

Water absorbs a great deal of heat for a small temperature rise, which is why it is used as an engine coolant and warms and cools slowly.