Glossary

AbsorptionWhen a material takes in a wave's energy instead of reflecting or transmitting it, often converting it into heat.

AccelerationThe rate at which an object's speed or direction changes over time.

Acceleration due to gravityThe rate at which gravity speeds up a falling object, about 9.8 meters per second squared near Earth's surface, the same for all masses in a vacuum.

Action-reaction pairTwo equal, opposite forces that occur when two objects interact, each acting on a different object.

Air resistanceA force caused by air pushing back against a moving object, which can slow falling objects depending on their shape and surface area.

AirbagA safety device that inflates during a crash to slow a passenger's motion more gently and absorb energy.

amorphousDescribing a solid material whose atoms or molecules are arranged in a disordered, non-repeating way, like glass or plastic.

AmplitudeThe height of a wave from its resting position to its peak; bigger amplitude means the wave carries more energy.

Analog signalA signal that varies smoothly and continuously, like the natural vibration of a guitar string.

Analog signalA signal that represents information as a smooth, continuously varying wave, like the grooves on a vinyl record.

atomThe smallest basic unit of an element, like a single tiny building block of matter.

attractTo pull toward something else, like opposite magnetic poles pulling toward each other.

Attractive forceA force that pulls objects toward each other rather than pushing them apart; gravity is always attractive.

balanced chemical equationA chemical equation where the same number of each type of atom appears on both sides of the arrow.

Balanced forcesForces acting on an object that cancel each other out, resulting in no change in motion.

biodegradableAble to break down naturally into harmless substances over time through the action of living organisms.

BitThe smallest unit of digital information, represented as either a 1 or a 0.

Braking distanceThe distance a vehicle travels while slowing to a stop.

Chemical makeupThe specific type of particles a substance is made of, which determines properties like the temperature at which it changes state.

chemical propertyA trait that only shows up when a substance undergoes a chemical change, such as flammability or reactivity with acid.

chemical reactionA process where atoms rearrange to form one or more new substances with different properties than the starting materials.

circuitA complete path that allows electric current to flow from a power source, through components, and back again.

closed systemA system where no matter can enter or leave, allowing an accurate before-and-after mass comparison.

CollisionAn event in which two or more objects strike each other, often transferring energy and force between them.

Collision damageThe harm caused during an impact, influenced heavily by speed and, to a lesser degree, mass.

compassA tool with a free-spinning magnetized needle that lines up with Earth's magnetic field to point toward magnetic north.

CondensationThe phase change from gas to liquid as particles lose energy and pull closer together.

ConductorA material, like most metals, that allows thermal energy to flow through it quickly and easily.

Conservation of energyThe principle that energy cannot be created or destroyed, only transformed or transferred between objects and forms.

Constant speedMoving the same distance in each equal time interval, shown as a straight line on a distance vs. time graph.

coreA piece of material, often iron, placed inside a coil of wire to strengthen the magnetic field it produces.

Crumple zoneA part of a car designed to crush during a crash, absorbing and spreading out kinetic energy to protect passengers.

crystal latticeA repeating, orderly 3D pattern of atoms or ions, like the structure found in table salt or diamond.

crystalline structureA solid material with atoms or ions arranged in an orderly, repeating 3D pattern.

DataRecorded measurements, like distance and time, used to study and predict motion.

DecelerationA decrease in speed over time, a type of acceleration in the opposite direction of motion.

densityHow much mass is packed into a certain amount of space (mass divided by volume).

Design constraintA limit an engineer must work within when building something, such as cost, size, or available materials.

Design criteriaThe specific requirements a device must meet to be considered successful, such as "keeps ice from melting for 6 hours."

Digital signalA signal that represents information as a sequence of discrete values, usually 1s and 0s (bits).

DistanceThe total length of the path an object has traveled.

Distance vs. time graphA graph that shows how an object's distance from a starting point changes over time.

electric chargeA basic property of matter (positive or negative) that causes electric and magnetic forces between objects.

electric currentThe flow of electric charge through a wire or circuit, usually carried by moving electrons.

electric fieldThe invisible region of space around a charged object where it can push or pull on other charged objects.

electromagnetA magnet created by electric current flowing through a coil of wire, which can be turned on and off and adjusted in strength.

Electromagnetic spectrumThe full range of electromagnetic waves, from long, low-frequency radio waves to short, high-frequency gamma rays.

Electromagnetic waveA wave made of vibrating electric and magnetic fields that can travel through empty space without a medium.

EncodeTo convert information, like sound or images, into a pattern a wave can carry.

endothermic reactionA chemical reaction that absorbs thermal energy, making its surroundings feel colder.

Energy transferThe movement of energy from one object or form to another.

Energy transformationThe process of energy changing from one form into another, such as potential energy changing into kinetic energy.

Equal and oppositeDescribes two forces that have the same strength but point in opposite directions.

Evaporation/BoilingThe phase change from liquid to gas as particles gain enough energy to escape each other's attraction.

Evidence of energy transferObservable clues, such as changes in motion, temperature, or sound, that show energy has moved between objects.

exothermic reactionA chemical reaction that releases thermal energy, making its surroundings feel warmer.

ferromagnetic materialA material, such as iron, nickel, or cobalt, whose electrons can line up to make the material strongly magnetic.

Fiber optic cableA thin strand of glass that transmits digital information as pulses of light over long distances.

FieldAn invisible region of space around an object where its force, like gravity, magnetism, or electric charge, can affect other objects without touching them.

flammabilityA chemical property describing whether a substance will catch fire and burn.

ForceA push or a pull that can change an object's motion.

Force diagramA drawing that uses arrows to show the direction and relative strength of forces acting on an object.

Frame of referenceA reference point plus a direction, used together to fully describe an object's motion.

FreezingThe phase change from liquid to solid as particles lose energy and lock into fixed positions.

FrequencyThe number of complete waves that pass a point in one second, measured in hertz (Hz).

FrictionA force that resists motion between two surfaces that are touching and sliding against each other.

FrictionA force that resists motion between surfaces in contact, often converting some kinetic energy into heat.

GasA state of matter in which particles move freely with large spaces between them, expanding to fill any container.

Gas pressureThe force created when gas particles collide with the surfaces of their container; caused by particle motion.

gravitational fieldThe invisible region of space around any object with mass where it can pull other masses toward it.

Gravitational potential energy (GPE)Stored energy an object has because of its height above the ground; the higher it is, the more it has.

GravityThe pulling force that pulls objects toward each other, and toward Earth in particular near its surface.

HeatThermal energy that is moving from a hotter object to a cooler object.

HeightThe vertical distance an object is above a chosen starting point, usually the ground.

inductionThe process by which a changing magnetic field near a wire can create, or induce, an electric current in that wire.

InertiaThe tendency of an object to resist changes to its motion, staying at rest or continuing in motion unless a force acts on it.

InsulatorA material, like foam, wood, or air, that resists the flow of thermal energy and slows it down.

Inverse relationshipA pattern where one quantity goes down as another goes up, such as gravitational force decreasing as distance increases.

Joule (J)The unit scientists use to measure energy, including gravitational potential energy.

Kinetic energyThe energy an object has because it is moving.

Kinetic energyThe energy an object has due to its motion, which increases rapidly as speed increases.

Kinetic energyThe energy an object has because it is moving; it depends on both mass and speed.

Kinetic energyThe energy an object or particle has because it is moving.

Kinetic energyThe energy of motion; in particles, faster movement means higher kinetic energy.

Latent heatThe thermal energy absorbed or released during a phase change that goes into rearranging particles rather than changing temperature.

law of conservation of matterThe scientific rule stating that matter cannot be created or destroyed in a chemical reaction, only rearranged.

LiquidA state of matter in which particles are close together but can slide past one another, so it holds a fixed volume but takes the shape of its container.

magnetic domainA tiny region inside a magnetic material where groups of electrons spin in the same direction, acting like a mini magnet.

magnetic fieldThe invisible region of space around a magnet where its force can be felt by other magnetic objects.

Magnetic forceAn attractive or repulsive force between magnets or magnetic materials that, like gravity, can act at a distance.

magnetic potential energyStored energy in a system of magnetic objects that depends on how they are positioned and how far apart they are.

magnetismA force caused by moving electric charges (like spinning electrons) that lets certain materials push or pull on each other without touching.

MagnitudeThe size or amount of something, such as how large a force or amount of damage is.

manufacturingThe process of using energy and chemical processes to turn raw materials into new, useful products.

MassThe amount of matter in an object, which determines how much inertia it has.

MassThe amount of matter in an object, which affects both its inertia and how much it accelerates under a given force.

MassThe amount of matter in an object; more mass means more gravitational potential energy at the same height.

MassThe amount of matter in an object, one of the two factors that determines the strength of gravitational force between two objects.

MassThe amount of matter in an object; more mass generally requires more total thermal energy to cause the same temperature change or phase change.

MediumThe material — like air, water, or a solid — that a mechanical wave travels through.

MeltingThe phase change from solid to liquid as particles gain enough energy to break free of fixed positions.

melting point / boiling pointThe specific temperature at which a substance changes from solid to liquid, or liquid to gas.

microplasticA tiny fragment of plastic, often smaller than a grain of rice, that forms as larger plastic items break down.

moleculeTwo or more atoms bonded together, like O2 (two oxygen atoms) or H2O (water).

MomentumA property of a moving object based on its mass and velocity, which is transferred and conserved during collisions.

MotionA change in an object's position over time, compared to a reference point.

natural materialA material that occurs in nature and is used with little or no chemical alteration, like wood, cotton, or wool.

natural resourceA material or substance from the Earth, like petroleum, minerals, or plants, that people use to make other things.

Newton's third lawThe scientific law stating that for every action force, there is an equal and opposite reaction force.

NoiseUnwanted interference or errors that distort a signal during transmission.

nonrenewable resourceA natural resource, like fossil fuels, that is used up much faster than it can be replaced by nature.

oxidationA chemical reaction, like rusting, where a substance reacts with oxygen to form a new compound.

Particle motionThe constant movement — vibrating, sliding, or flying — of the tiny particles that make up all matter.

PerspectiveThe particular point of view from which someone observes and describes motion.

petroleumA natural, oily liquid found underground that is refined into fuels and used as a raw material for plastics.

Phase changeA transformation of a substance between solid, liquid, and gas states, caused by adding or removing thermal energy.

physical changeA change in a substance's form or state (like melting or tearing) where no new substance is created.

physical propertyA feature of a substance you can observe or measure without changing what the substance is, like color, odor, or density.

physical propertyA trait you can observe or measure without changing what the substance chemically is, such as color, density, or boiling point.

PitchHow high or low a sound seems, determined by the frequency of the sound wave.

poleOne of the two ends of a magnet (north or south) where the magnetic field is strongest.

polymerA material made of long chains of repeating molecular units, common in plastics.

PositionThe exact location of an object at a certain moment, usually described using a reference point.

PositionWhere an object is located, especially how high or low it sits compared to a reference point like the ground.

Potential energyEnergy that is stored and waiting to be used, rather than energy that's currently making something move.

PredictionA scientific estimate about what will happen, based on patterns in data.

PrismA transparent object that splits white light into its full spectrum of colors by refracting each wavelength differently.

Proportional relationshipA relationship where one quantity changes at the same rate as another, like how kinetic energy doubles when mass doubles.

Protective featureA design element, like a seatbelt or crumple zone, meant to reduce injury during a collision.

Radio waveA low-frequency electromagnetic wave commonly used to transmit information wirelessly, such as for wifi or cell phones.

Rate of heating/coolingHow quickly a material's temperature changes when it gains or loses thermal energy, which differs by material type.

raw materialA natural resource, like petroleum, sand, or plant matter, that is processed to make other products.

rearrangeTo connect atoms in a different pattern or combination, without creating or destroying any of them.

Reference pointA fixed object or location you compare another object's position to, in order to tell if it's moving.

Reference pointThe starting level you measure height and potential energy from, such as the ground or the floor.

ReflectionWhen a wave bounces off a surface instead of passing through it.

RefractionThe bending of a wave as it passes from one medium into another and changes speed.

RefractionThe bending of light as it passes between materials of different densities, such as air and water.

Relative motionHow an object's movement appears to change depending on what you compare it to.

repelTo push away from something else, like two like magnetic poles pushing apart.

RestraintA device, like a seatbelt, that applies a force to keep an object moving together with another object.

SlopeThe steepness of a line on a graph; on a distance vs. time graph, slope equals speed.

solenoidA coil of wire, often wrapped around a core, that produces a magnetic field when electric current flows through it.

SolidA state of matter in which particles are packed tightly and mostly vibrate in fixed positions, giving it a definite shape.

Sound energyEnergy carried by vibrations traveling through the air, produced when objects collide or shake.

SpeedHow fast an object's position changes, calculated as distance divided by time.

Squared relationshipA relationship where one quantity increases with the square of another, like how kinetic energy quadruples when speed doubles.

State of matterOne of the forms matter can take — commonly solid, liquid, or gas — determined by how particles move and how far apart they are.

StationaryNot moving relative to a chosen reference point.

sustainabilityMeeting human needs in a way that doesn't damage the environment or use up resources for future generations.

synthetic materialA material made through a human-designed chemical process, usually starting from a natural raw material.

SystemA group of objects being studied together, such as a truck and everything on it.

SystemTwo or more objects being considered together, especially when studying how they interact and exchange energy, like a ball and Earth, or two magnets.

TemperatureA measure of the average kinetic energy (average speed) of the particles in a substance — basically, how fast the particles are jiggling or zooming around on average.

Thermal (heat) energyEnergy related to the temperature of an object, often produced by friction.

Thermal energyThe total kinetic energy of all the moving, vibrating, and colliding particles in a substance.

Total internal reflectionThe way light bounces repeatedly off the inner walls of a fiber optic cable, keeping it traveling forward instead of escaping.

TransmissionWhen a wave passes through a material, like light passing through clear glass.

Unbalanced (net) forceThe overall force remaining after all forces on an object are combined, causing a change in motion.

Universal law of gravitationThe rule that any two objects with mass attract each other, with the force depending on their masses and the distance between them.

VacuumA space completely empty of matter; light can travel through it, but sound cannot.

Visible lightThe narrow band of the electromagnetic spectrum that human eyes can detect, seen as the colors of the rainbow.

WaveA disturbance that carries energy from one place to another without permanently moving the matter it travels through.

WavelengthThe distance from one point on a wave to the exact same point on the next wave, like peak to peak.