Science Test 1

models

mental picture or representation that helps us explain the world around us
1. explain previous observations
2. makes testable predictions about things that have not yet been observed
ex: diagram, physical drawing, equation, analogy

macroscopic vs. miscroscopic properties

1. properties that can be detected by the human body/eye and are observable by human instruments
ex: size, volume, shape, density

2. of the size that can't be detected with the human body/eye and is not observable by human instruments
ex: size of an atom, average kinetic energy of an atom, speed of atom inside a gas

density

how much matter in a certain amount of space
inherent prperty of a material
D = m/v

solids

atoms are tightly packed together

liquids

atoms slide past eachother, still sticking ocasionally

gases

atoms totally seperate and move freely past eachother

temperature

not energy
measurement of heat or energy

thermal equilibrium

when two objects in contact come to the same temperature

melting point

temperature at which a certain material turns from solid to liquid or liquid to solid

boiling point

temperature at which a certain material turns from a liquid to gas or gas to liquid

heat

form of energy
flows from high to low temperature
neither created nor destroyed
heat flow depends on:
1. temperature difference between objects
2. mass of object
3. material that object is made of

internal energy

sum of all energies in an object

calorie

amount of energy that needs to be transferred to water to raise the temperature of 1 gram of water by 1 celsius degree

speciific heat capacity

quantity of heat required to change the temperature of a unit mass by 1 celsius degree
low heat capacity = less energy needed for temperature change, so the temperature changes quickly
high heat capacity = more energy needed for temperature change, so the temperature changes slowly

Latent Heat

how much heat is required to turn a certain amount of material from one state to another

latent heat of fusion

solid to liquid/liquid to solid
Q = m x Hf

Latent Heat of Vaporization

liquid to gas/gas to liquid
Q = m x Hv

Conduction

transfer of energy by touching
happens between collisons of atoms and electrons

Conductor

transfers heat and electricity well
ex: metals - gold, silver, copper

Insulator

transfers heat and electricity poorly
ex: wool, wood, paper, air

Convection

transfer of heat or energy in gas or liquids by means of currents in the heated fluid
as fluid moves it carries energy
fluid heated from below so molecules move faster then fluid becomes less dense and moves upwards then the cold liquid replaces liquid previously at the bottom
ex: winds and clouds, ocean currents, molten material in earths core

radiation

The transfer of energy by electromagnetic waves(light)
low energy - infrared/radiowaves
middle energy - visible lights
high energy - ultra violet/x-ray
shorter wavelength = high energy
any substances above absolute zero emits radiation

absorbers

dark colored objects/clothing that aborb light well and heat up faster

emitters

Objects that have the ability to emit radiation efficiently
good absorber = good emitter
cool down faster

reflectors

light colored objects/clothing that light bounces off of, so they don't heat up as quickly