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When temperature increases…
molecules start to move around faster and increase
when temperature decreases…
molecules start to slow down and shrink
What happens if hot and cold molecules are close together?
the higher temperatures go down, the lower temperatures go up
What is ‘Abolute 0’
-273 degrees C or 0 Kelvin
What does Kelvin do?
reads the lowest temperatures in the universe
Energy transfer
when two things have different temperatures and are in contact, heat leaves the warmer one and enters the colder one
When does energy transfer happens faster?
when there is a great temperature difference
thermal energy
heat wants to go from where there’s a lot to where there’s a lot less
thermal equilibrium
after a few seconds (when things that are relatively close in temperature), the heat transfer slows down and it doesn’t feel as dramatic
What impacts heat transfer?
mass AND material
what is a calorie ( c ) ?
the amount of heat required to raise 1 gram of water by 1 degree Celsius
thermal inertia
objects tend to stay at their current temperature unless acted on by an outside force
what objects have the highest specific heat
water (also hydrogen and helium)
what objects have low specific heat?
metals
what does it mean to have a high specific heat?
what does it mean to have a low specific heat?
an objects resists changing temperature well
an object easily changes temperature
how does specific heat impact the climate?
water that’s close to the land draws heat off of it during the day, and keeps it warm at night
when is water most dense?
4 degrees Celsius
what does the density of water do in our everyday lives?
makes it so that ice doesn’t sink
where is thermal expansion used in our everyday lives?
thermostats, mercury thermometers
conduction
heat transfer within a substance or from one substance to another if making contact
what are some good conductors?
metals, especially silver and copper
why isn’t silver used in wires?
too expensive
what are some good insulators?
wood, cotton, fiberglass, plastic, anything with lots of gaps (air pockets - porous materials)
convection
travels through currents in a fluid (liquids and gases). hot molecules move faster and faster. air molecules rise because they get more dense
wind
caused by a difference in temperature between two places. as hot air rises, it creates a vacuum that draws in air from other places
ocean winds
winds blows towards the ocean on a summer night and towards land during the day (water has high specific heat, and requires much more energy/time to change its temperature, especially since the ocean has so much mass)
convection in lakes
create turnover as the water temperature changes, which churns up microorganism which creates food
what is radient energy?
energy that is emitted from something that travels through the air towards you, shows up as waves
what is radiation?
any energy coming through the air
frequency and wavelength are ______
proportional
high temperatures =
shorter wavelengths
low temperatures =
longer waves
good absorbers are….
also good emitters
what colors ABSORB more energy?
dark colors
what colors REFLECT more energy?
light colors
Newton’s Law of Cooling
when something hot and something cool meet, they will reach equilibriium (where hot will cool and cool will warm)
global warming
when the radient energy from the sun is striking the earth, and warms up and starts to release heat, although it isn’t as hot as the sun (when the atmosphere traps the sun’s rays)
greenhouse effect
radiation enters through the atmosphere/glass but cannot escape, making the inside/surface hotter, and hotter
what might happen if the earth continues to warm?
more hurricanes/tsunamis, hotter summers, colder winters, flooding, droughts
phase change involves…
a transfer of energy
what is evaporation?
process of going from a liquid to a gas.
increases in activity of molecules
is a cooling process because it removes heat from the object
what is a cooling process/what does it do?
removes heat from the object and transfers it to itself/something else
what is condensation?
process of changing from a gas to a liquid
molecules slow down, and shrink/condense
warming process because it is giving energy onto the surface struck
what is a warming process/what does it do?
releases heat from a phase change into the object it’s touching
what are examples of evaporation?
a person sweating, a dog panting, a bowl of water
what are examples of condensation?
liquid on a drink bottle, clouds, water droplets on a window, fog
what is boiling?
process of changing a liquid to a gas
happens BELOW the surface of the water (from bottom)
a cooling process
how does high pressure effect the boiling point of water?
high pressure increases the boiling point of water
why do we put lids on our pots?
to increase the pressure
because even though it takes longer to boil, once it begins to boil, the water can get even hotter
how does air pressure affect cook times?
at low pressure/high elevation, water boils at a lower temperature, so food takes longer to cook
what is freezing?
process of changing a liquid to a solid
molecules slow down, and give energy away - making it a warming process
what are some ways to lower the freezing point?
Salt (lowers freezing temperature)
coal dust, sand, sugar, antifreeze
what is the equation for calories?
Q=mc(change in T)
m = mass
c = cal/gC
change in time = degrees Celsius
Q = calories
what is melting and freezing at the same time an example of?
regelation
what is an example of regelation?
snowballs (temperature outside causes them to freeze, but when they make contact with us, it melts due to our body heat)
what is the range of Celsius?
What is the range for Farenheit?
0-100
180
why is steam more dangerous to touch when it is hot than hot water?
because steam has more molecules, so it has more energy to give off to teh object it is touching
