| A | B |
|---|
| absolute zero | the temperature at which no more energy can be removed from matter |
| acceleration | the rate at which velocity changes |
| air resistance | the fluid friction experienced by objects falling through the air |
| Archimedes' principle | the rule that the buoyant force on an object is equal to the weight of the fluid the object displaces |
| average speed | the overall rate of speed at which an object moves; calculated by dividing the total distance an object travels by the total time |
| balanced forces | equal forces acting on an object in opposite directions |
| barometer | an instrument used to measure atmospheric pressure |
| Bernoulli's principle | the rule that a stream of fast-moving fluid exerts less pressure than the surrounding fluid |
| boiling | vaporization that occurs on and below the surface of a liquid |
| buoyant force | the upward force exerted by a fluid on a submerged object |
| Celsius scale | the temperature scale on which water freezes at 0 degrees and boils at 100 degrees |
| centipetal force | a force that causes an object to move in a circle |
| change of state | the physical change of matter from one state to another |
| chemical energy | the potential energy stored in chemical bonds |
| combustion | the process of burning a fuel to produce thermal energy |
| compound machine | a device that combines two or more simple machines |
| condensation | the change from the gaseous to the liquid state of matter |
| conduction | the transfer of heat from one particle of matter to another |
| conductor | a material that conducts heat well |
| convection | the transfer of heat by the movement of currents within a fluid |
| density | the mass of a substance contained in a unit of volume |
| efficiency | the percentage of the input work that is converted to output work |
| elastic potential energy | the energy of stretched or compressed objects |
| electrical energy | the energy of electric charges |
| electromagnetic energy | the energy of light and other forms of radiation |
| energy | the ability to do work or cause change |
| energy transformation | the process of changing one form of energy to another |
| evaporation | vaporization that occurs at the surface of a liquid |
| external combustion engine | an engine powered by fuel burned outside the engine |
| Fahrenheit scale | the temperature scale on which water freezes at 32 degrees and boils at 212 degrees |
| fluid | a material that can easily flow |
| fluid friction | friction that occurs as an object moveds through a fluid |
| force | a push or a pull exerted on an object |
| fossil fuel | a material such as coal that forms over millions of years from the remains of ancient plants and animals; burned to release chemical energy |
| free fall | the motion of a falling object when the only force acting on itis gravity |
| freezing | the change from the liquid to the solid state of matter |
| friction | the force that one surace exerts on another when the two surfaces rub against each other |
| fulcrum | the fixed point around which a lever pivots |
| gravitational potential energy | potential energy that depends on the height of an object |
| gravity | the force that pulls objects toward each other |
| heat | thermal energy that is transferred from matter at a higher temperature to matter at a lower temperature |
| heat engine | a device that converts thermal energy into mechanical energy |
| hydraulic system | a system that multiplies force by transmitting pressure from a small surface area through a confined fluid to a larger surface area |
| inclined plane | a simple machine that is a flat sloped surface |
| inertia | the tendency of an object to resist any change in its motion |
| input force | the force exerted on a machine |
| input work | the work done on a machine as the input force acts through the input distance |
| instantaneous speed | the speed of an object at one instant in time |
| insulator | a material that does not conduct heat well |
| internal combustion engine | an engine that burns fuel inside cylinders within the engine |
| International System of Units | a system of measurement based on multiples of ten and on estabilished measures of mass, length, and time |
| joule | a unit of work equal to one newton-meter |
| Kelvin scale | the temperature scale on which zero is the temperature at which no more energy can be moved from matter |
| kinetic energy | energy that an object has due to its motion |
| law of conservation of energy | the rule that energy cannot be created or destroyed |
| law of conservation of momentum | the rule that in the absence of outside forces the total momentum of objects that interact does not change |
| lever | a simple machine that consists of a rigid bar that pivots about a fixed point |
| lift | an upward force |
| machine | a device that changes the amount of force exerted, the distance over which a force is exerted, or the direction in which force is exerted |
| mass | the amount of matter in an object |
| matter | anything that has mass and takes up space |
| mechanical energy | kinetic or potential energy associated with the motion or position of an object |
| melting | the change from the solid to the liquid state of matter |
| meter | the basic SI unit of length |
| momentum | the product of an object's mass and velocity |
| motion | the state in which one object's distance from another is changing |
| net force | the overall force on an object when all the individual forces acting on it are added together |
| newton | a unit of measure that equals the force required to accelerate 1 kilogram of mass at 1 meter per second per second |
| nuclear energy | the potential energy stored in the nucleus of an atom |
| output force | the force exerted on an object by a machine |
| output work | the work done by a machine as the output force acts through the output distance |
| pascal | a unit of pressure equal to 1 newton per square meter |
| Pascal's principal | the rule that when force is applied to a confined fluid, the increase in pressure is transmitted equally to all parts of the fluid |
| plate | one of the major pieces that make up Earth's upper layer |
| potential energy | stored energy that results from the position or shape of an object |
| power | the rate at which work is done |
| pressure | the force exerted on a surfaced divided by the total area over which the force is exerted |
| projectile | an object that is thrown |
| pulley | a simple machine that consists of a grooved wheel with a rope or cable wrapped around it |
| radiation | the transfer of energy by electromagnetic waves |
| reference point | a place or object used for comparison to determine if an object is in motion |
| refrigerant | the substance that absorbs and releases heat in a cooling system |
| rolling friction | friction that occurs when an object rolls over a surface |
| satellite | any object that orbits another object in space |
| sliding friction | friction that occurs when one solid surface slides over another |
| slope | the steepness of a line on a graph, equal to its vertical change divided by its horizontal change |
| specific heat | the amount of heat required to raise the temperature of 1 kilogram of a material by 1 kelvin |
| speed | the distance an object travels per unit of time |
| state | one of the three forms - solid, liquid, or gas - in which most matter on Earth exists |
| static friction | friction that acts on objects that are not moving |
| temperature | the measure of the average kinetic energy of the particles in matter |
| terminal velocity | the greatest velocity a falling object can achieve |
| theory of plate tectonics | the theory that pieces of Earth's outer layer are in constance motion |
| thermal energy | the total potential and kinetic energy of the particles in an object |
| unbalanced forces | forces that produce a nonzero net force, which changes an object's motion |
| velocity | speed in a given direction |
| weight | the force of gravity on an object at the surface of a planet |
| work | force exerted on an object that causes it to move |
