How are atoms arranged
in an array called crystals
what are non crystalline solids called
amorphous structures
4 types of chemical bonds
Ionic
Covalent
Mettalic
Ver der walls
What affects the properties of a solid
the type of chemical bond used
Density definition
Amount of mass per unit volume of a material.
Density formula
Mass/volume
units of density
kg/m3 or gm/cm3.
Weight density formula
weight over volume or 9.8 x density
Unit of weight density
N/m3
What does density depend on
mass of atoms
spacing between atoms
What does not matter for density?
the amount of material you have
What changes when something experiences external force
size and shape
what is elasticty
How well an object returns to its original shape after being changed by force
What are objects that don't return to their original shape called
inelastic
Hookes law
The extension of a spring is directly proportional to the force applied to it.
What is it called when something is pulled
tension
What is it called when something is squished
compression
Pressure definition
The force per unit area that one object exerts on another
Pressure formula
force over area
unit of pressure
N/m2, lb/ft2, or Pa (Pascals)
What does pressure depend on
the area the force is distributed to
Pressure in a liquid definition
the force per unit area that a liquid exerts on a object
What does pressure in a liquid depend on
depth
what doesn't pressure in a liquid depend on
volume
What direction does pressure move in liquids
all directions
How is pressure applied to a submerged object
perpendicular to the sides of the object
Bouyancy definition
apparant loss of weight of a submerged object proportional to the weight of the water displaced. This is equal to the amount of force pushing up onto the object
When does an object sink
when the weight of an object is greater than the bouyant force
When does an object float
When the weight of an object is lighter than the buoyant force
Archemedes principal
States that an immersed body (completely or partially) is buoyed up by a force equal to the weight of the fluid it displaces.
Applies to gases and liquids.
What type of fluids exert a great buoyant force?
denser fluids
How does archemedes principal apply in air
The more air an object displaces, the greater the buoyant force on it.
If an object displaces its weight, it
hovers at a constant altitude.
If an object displaces less air, it
descends.
Pascals principal
Pressure applied to one point in an enclosed fluid at rest is applied undiminished to the rest of the fluids
What is a fluid
liquids and gases
Surface tension
All molecules in a liquid are attracted to each other. The molecules on the surface are not attracted by the air and creat a greater tension on the surface of the liquid than in the liquid because of it.
What 3 factors affect surface tension
type of liquid
what's mixed with the liquid
temperature of the liquid
Cappiularity definition
The rise of a liquid in a fine, hollow tube or in a narrow space`
what affects capilarity
The weight of the liquid and the narrowness of the tube
What are atoms
Atoms are the building blocks of matter
what is an element
a material composed of only one type of atom
How many elements are there
115
Main 5 elements
oxygen
hydrogen
carbon
nitrogen
calcium
How are heavy atoms created
supernovas
How do atoms move
atoms move in perpetual motion with there being less movement in solids and more in liquids and even more in gases
What is Brownian motion
the evidence for the existance of atoms
What is a compoud
a substance made of more than one element
What is the atmosphere
an ocean of air
What is atmospheric pressure caused by
Caused by weight of air
Varies from one locality to another
Not uniform
Measurements are used to predict weather conditions
What is atmospheric pressure
pressure exerted in object submerged in air
What does a barometer measure
atmospheric pressure
boyels law
pressure and volume of a gas are inversely proportional
How does something float
if its lighter than air(helium balloons)
where is air less dense
higher up
Bernoullis principal
If the speed of a fluid increases pressure decreases
what are streamlines
lines representing fluid motion
laminar flow
smooth flow
Temperature definiton
number corrsponding to the warmth or coldness of an object`
What is temperature proportional to
the average transitional kinetic energy per partial of an object`
Three temperature scales
farenheight
celcius
kelvin
how is heat measured
calories or joules
specific heat capacity`
4.18 joules of heat are required to change the temperature of 1 gram of water by 1 Celsius degree
Thermal inertia
resistance of a substance to a change in temperature
What substance has a high specific heat capacity
water
Thermal expansion
substances expand in heat and contract in the cold
Thermal expasion is greater in liquids or solids?
liquids
What liquid defies thermal expansion
ice because it expands when it freezes
What happens when the temperature of a gas changes
the volume changes
absolute 0
no kinetic energy
what is internal energy
energy at the partial level of a substance
First law of thermodynamics
energy can neither be created nor destroyed
increasing mechanical work increases internal energy
adiabatic process
compessing or expanding a gas while no heat enters the system
No heat added=increase in internal energy is because of work done in the system
Second law of thermo dynamics
Heat never flows from cold to hot unassisted.
What is a heat engine
any device that converts internal heat into mechanical work
How much heat in a heat engine can be transformed into work
some of it
Parts of heat engine
a reservoir of heat at a high temperature.
a sink at lower temperature.
How a heat engine works
gathers heat from the reservoir at high temperature.
converts some of this heat into mechanical work.
expels the rest of the heat to the sink at lower temperature.
CAn ideal efficiency be reached
no because of friction
Entropy
the amount of disorder in a system
how does entropy decreas
if work is done to a system
Three ways to transfer heat
convection
condution
radiation
conduction
the transfer of heat through the collision of molecules especially in solids
what makes a good condutor
things that conduct heat quickly like metal
what is an insulator
things that don't conduct heat well
Convection
Transfer of heat involving the bulk motion of fluids
RAdiation
energy transefferd from the sun through a vaccume
what does the Wave length of radiation depend on
the frequency of the waves
What material reflect radiant energy
shiny ones