Question | Answer |
centripetal acceleration | acceleration of an object towards the center of a curved path |
centripetal force | a force directed toward the center of a circle for an object moving in a circular motion |
friction | a force that opposes motion between two touching surfaces |
law of gravitation | states that any two masses exert a force one each other, which depends on the mass of the two objects and the distance between them |
momentum | a property that a moving object has because of its mass and velocity |
Newton's second law of motion | states that a net force acting on an object causes the object to accelerate in the direction of the net force |
Newton's third law | describes action-reaction pairs; to every force there is an equal and opposite reaction force |
weight | gravitational force exerted on an object by earth |
chemical potential energy | energy stored in chemical bonds |
elastic potential energy | energy stored by things that stretch, twist, or compress |
gravitational potential energy | energy stored by things attracted to each other by the force of gravity |
joule | SI unit of energy |
kinetic energy | energy in the form of motion; depends on the mass and velocity of the object |
law of conservation of energy | states that energy can never be created or destroyed |
mechanical energy | sum of potential and kinetic energy in a system |
potential energy | stored energy due to position; can be converted to kinetic energy when something acts to release it |
compound machine | combines two or more simple machines |
efficiency | measure of how much of the work put into a machine is changed into work done by a machine |
effort force | force exerted on a machine that is used to do work |
inclined plane | simple machine that consist of a sloping surface, such as a ramp, that reduces the amount of force needed to lift something by increasing the distance over which the force is applied |
lever | a simple machine made from a bar that is free to pivot around a fixed point |
machine | a device that makes doing work easier by increasing the force applied to n object, by changing the direction of an applied force, or by increasing the distance over which the force can be applied |
mechanical advantage | number of times a machine multiplies the effort force applied to it |
power | amount of work done, or the amount of energy transferred, in a certain amount of time |
pulley | a simple machine that consists of a grooved wheel with a rope, chain, or cable that runs along a groove, changes the direction of the effort force, and can be fixed of moveable |
resistance force | force applied by a machine to overcome resistance |
screw | a simple machine that consists of an inclined plane wrapped in a spiral around a cylindrical post |
simple machine | machine that does work with only one movement; includes the lever, pulley, wheel and axle, inclined plane, screw, and wedge |
wedge | a simple machine that consists of an inclined plane with one or two slopping sides |
wheel and axle | a simple machine that consists of two different-sized wheels that rotate together |
work | transfer of energy the occurs when a force makes an object move; measured in joules |
wave | a rhythmic disturbance that transfers energy through matter or space; exists only as long as it has energy to carry |
medium | any material or combustion that a wave can transfer energy through |
transverse wave | a type of wave, such as a water wave, where the matter in the medium moves back and forth at right angles to the direction the wave travels |
compressional wave | a type of wave where the matter moves back and forth in the same direction the wave travels; has compressions and rarefractions |
crest | highest point of a transverse wave |
trough | lowest point of a transverse wave |
refraction | the least dense region of a compressional wave |
wavelength | distance between one point on a wave and the nearest point just like it on the following wave; as frequency wavelength always decreases |
frequency | measures how many wavelengths pass a fixed point each second, and is expressed in hertz |
aplitude | a measure of energy is carried by a wave |
conduction | transfer of energy through matter by colliding particles;takes place because particles are in constant motion |
convection | transfer of energy by the motion of heated particles in a fluid |
radiation | transfer of energy in the form of electromagnetic waves |
insulators | materials such as fleece or fiberglass that do not allow heat to move easily through them |
nuclear fusion | process of fusing together two atomic nuclei with low masses to form one nucleus with a larger mass |
nuclear fission | process of splitting a large atomic nucleus into two nuclei with smaller masses |
chain reaction | an ongoing series of fission reactions |
tracer | a radioisotope that is used to find or keep track of molecules in an organism |
critical mass | amount of fissionable material required so that each fission reaction produces approx. one more fission reaction |
opaque | a material that absorbs or reflects all light |
translucent | a material that allows some light to pass through, but not enough to see objects clearly |
transparent | a material that transmits almost all the light striking it so that objects can be seen clearly through it |
index of refraction | property of a material indicating how much light slows down when traveling in a material |
mirage | an image of a distant object that results when air at ground level is much warmer or cooler than the air layers above it, which makes the image refract and appear at a different loction from where it usually is |
pigment | colored material that absorbs some colors, and reflects |
Charging by contact | process of transferring charge by touching or rubbing two surfaces |
charging by induction | process of transferring charge between objects by bringing a charged object by a neutral object |
circuit | a CLOSED conducting loop through which an electric current can run through |
conductor | material such as copper wire, through which an excess of electrons can easily move though |
electrical current | flow of electric charge through a wire or an conductor; mesured in amperes |
electrical power | the rate at which electrical energy is converted into another form of energy; expressed in watts |
insulator | material that doesn't allow electrons to move easily through |
kilowatt-hour | a unit of electrical energy which is, 100 watts of power used in one hour |
law of conservation of charge | states that charge can be transferred from one object to another, but can't be created or destroyed |
ohm's law | states that the current in a circuit equals the voltage difference divided by the resistance |
parallel circuit | a circuit in which electric current has more than one path to follow |
resistance | tendency for a material to oppose electron flow, and change electrical energy into light |
series circuit | a circuit in which current only has one path to flow |
static electricity | electricity generated when two objects rub against each other |
voltage difference | a push that causes electrical charges to flow through a conductor; measured in volts |