definitions Flashcards
vector
a physical quantity that has both magnitude and direction
resultant
the single vector which has the same effect as all the component vectors together would have
maximum resultant
obtained when two vectors act in the same direction
minimum resultant
obtained when 2 vectors act in opposite directions
distance
length of the path actually taken
displacement
a body’s change in position
speed
rate of change of distance moved
instantaneous speed
speed at a particular moment
velocity
rate of change of position
instantaneous velocity
the velocity at a particular moment
acceleration
the rate of change of velocity
pure substance
consists of one type of substance only and are made up either of elements or compounds, have a constant composition
element
a substance that cannot be broken down into simpler substances. made up of only one type of atom
compound
formed when two or more pure substances combine chemically with each other in a fixed ratio
mixture
combination of two or more substances in which the substances retain their individual properties. can be present in any ratio
homogeneous mixture
a mixture in which the composition of the mixture is the same throughout and consists of two or more substances in the same phase
heterogeneous mixture
a mixture in which the composition of the mixture is not uniform
temperature
an object is proportional to the average kinetic energy of its particles
melting point
temperature at which a solid changes phase to become a liquid
freezing point
temperature at which a liquid changes phase to become a solid
boiling point
temperature in which a liquid changes phase to become a gas, or a gas changes into a liquid
evaporation
takes place at any temperature at surface only
scalar
a physical quantity which has a magnitude only
sublimation
when a substance changes straight from a solif to a gas
atomic number
the number of protons in an atom
mass number
the number of protons plus neutrons in an atom
isotopes
atoms of the same element which have different mass numbers. they have the same nuber of protons in the nucleous, but a different number of neutrons
ion
a charged atom
cation
a positively charged atom because it has lost an electron
anion
a negatively charged atom because it has gained an electron
