sevenatenine

2008-09-08T20:54:00.000-07:00

HELLO COWS :D

LET US BE THINKERS!

the thermal flask is a EXTRAORDINARY invention it uses almost all of the thermal physics knowledge to prevent heat from escaping.DO YOU KNOW WHY thermal flasks with glass coating works better than the ones without?

TELL ME WAEEEEEEE

now,imagine if you're a SPYYYYY, and your only tool at the moment is a glass cup (budget case:D) now you're suppose to eavesdrop on someone in the next room.would it be better to listen with a cup filled with water since the particles will be denser or just an empty cup?

TELL ME WHYYYYY :D

2008-09-05T02:57:00.000-07:00

in case you didn't understand some stuff
watch the cartoon videos!

measurement of temperature

potential energy

heat as energy

2008-09-05T01:43:00.000-07:00

unit 9 thermal properties of matter
internal energy;it is the total amount of energy of the particles of matter.
comprising of kinetic energy( vibration of particles),the higher the temperature,the more vigorous the vibration, and, potential energy(stretching and compressing of intermolecular bonds)

melting and boiling graph of water.
these are the pairs of opposites:
melting- when a solid changes to liquid upon heating
solidification-when a liquid changes to solid upon freezing

boiling-when liquid changes to gas upon heating
condensation-when gas changes to liquid upon cooling

melting and solidification
solid melts when the strong intermolecular bonds are broken by the thermal energy supplied.Hence thermal energy is used to break such bonds,thats why from the graph,the temperature remains the same in the process of melting.

vice versa,when liquid solidifies due to freezing,the molecules come together and forms an intermolecular bond,during this process,thermal enrgy is given out,hence the temperature remains the same during solidification.

boiling and condensation
boiling works the same way as melting,thermal energy pushes and seperates the molecules away on the surrounding atmosphere,thermal energy is used.As such,the intermolecular bond is negligible.hence the state is changed to gaseous.

vice versa,when gas condenses,the molecules come closer together to form a intermolecular bond,heat is given out.Hence it becomes a liquid

EVAPORATION;only takes place between liquid and gases

watch the explaination!

factors affecting evaporation:
temperature-the higher the temperature the quicker the rate of evaporation
humidity in the surrounding air-when the air is humid (a lot of water vapour),the rate of evaporation decreases
surface area of liquid-the larger the surface,the quicker the rate of evaporation.this is due to the exposed surface,where the molecules can escape
movement of air-the greater the movement the greater the rate of evaporation
pressure-the lower the pressure the quiker the rate of evaporation
boiling points-the lower the boiling point the faster the rate of evaporation

2008-09-05T00:59:00.000-07:00

Application of thermal energy transfer
making use of thermal energy knowledge.

application of conduction

comparing the singe glazing and double glazing.

to prevent this,man has designed roof space

even,ventillators.

common appications:
cooking utencils -kettles,pots,pans are usually made of aluminum or stainless steel.since metal is a good conductor,which takes less time to heat up to high temperature

thermometers-the tip of the thermometer is made of metal,since metal conducts heat readily to give accurate readings

handles of heating equipment-are usually made of insulators,such as plastic.this is in order to prevent handling it without scorching our hands

wollen clothes- since wool is an insulator,it keeps us warm in winter

applications of convection:

common applications :electric kettle,water heaters,air conditioners,refrigerator.

air conditioners are usually placed at the top of the room since hot air rises,the air conditioners cools it.

application of radiation:

greenhouses-help plants grow better in cold climates.by day, the suns infrared passes through the roof of the green house,warming the contents of the greenhouse.the infrared emitted by the contents however are unable to penetrate out of the greenhouse.thus the trapped heat is trapped in the greenhouse,over time,the trap infrared builds up and the temperature rises

roofs- a thin foil of shiny metal is laid out,since shiny surfaces are bad absorbers and emitters,the house is able to maintain a regular comfortable temperature.

2008-09-04T22:58:00.000-07:00

UNIT 8 transfer of thermal energy
THREE METHODS
- conduction
-convection
-radiation

explanation of above pic:

conduction;transfer of thermal energy without any flow of material medium

when thermal energy is supplied to an end,the particles vibrate vigorously,about fixed positions, and collides with neightbouring particles,making them vibrate ( like a domino effect)thus the kinetic energy is transferred to neighbouring particles.

conduction is most efficient in metals,whereas in liquid and gases,it is inefficient because their particles are further apart as compared to solids.hence collision occurs less frequent.this is why air and water are poor conductors.

convection;transfer of thermal energy through currents of fluids(liquids and gases)
when water at the bottom of the pot is heated,it expands.The expanded water is less dense than the surrounding water,hence it rises,leaving the cooler water at the upper parts of the pot,to sink being denser.thus a movement(current) is formed due to the difference in its density.

convection can only take place in fluids!TIB(this is because) convection requires bulk movement of fluids,but solids can only vibrate about in fixed positions and are unable to move in bulks.

radiation;a continuous emission of infrared waves from the surface of all bodies,transmitted without the aid of a medium.(can take place in vacuum)

(click for larger image)
the heat that reaches the Earth from the Sun,is done so byt the process of radiation.Convection and conduction are impossible because of the vacuum between Earth and the Sun.

ALL OBJECTS absorb and emmit some radiant heat.
the hotter the object the greater amount of radiant heat.

all objects and surfaces absorb infrared radiation.the absorption causes temperature to rise

-dull,black surfaces absorb infrared radiation faster compared to shiny white surfaces.
-dull black surfaces are better emitters of infrared radiation than shiny white surfaces

factors affecting rate of infrared radiation.
colour- dull black surfaces are better absorbers and emitters of infrared radiation

surface temperature-the higher the temperature of the surface to the surrounding temperature,the higher the rate of infrared radiation

surface area-comparing two objects of equal weight and mass,the object with a larger surface area will emit infrared radiation at a higher rate

VIDEO TIME!

conduction

convection

radiation

2008-09-04T22:36:00.000-07:00

brownian motion
the random movemoents of liquids and gases
this is a result of an experiment to show brownian motion.

experiment:

when you look through the microscope

this is how it'll look like :D

2008-09-02T02:21:00.000-07:00

UNIT 7 ( kinetic model of matter)

MATTER is what makes up all objects/substances

- matter is something that occupies space

-matter exist in mainly 3 states ( meaning there are other states BUT I'll focus on these main 3)

you,me,buildings,air and even people you dislike are matters,even when they don't "matter"

STATES: ( not states of a country)
states- forms of matter ( the form they appear to you in)
3 main states:

SOLID
LIQUID
GAS

properties of SOLID

fixed shape & volume
normally hard
high density
incompressible

examples:alloys,diamond,wood,paper
because solids are hard,have a fixed shapes,volume and are high in density,they usually take a GREAT force to change its shape.my advice is don't knock your head against any type of solid.

properties of LIQUID

fixed volume
no fixed shape
high density
incompressible

examples:rain,oil

properties off GAS

no fixed shape
no fixed volume
low density
compressible

examples:steam,air

case example: water is a matter,it can exist in all three of these sates
when it is a solid, its is ICE
when it is a liquid,it is WATER
when it is a gas,it is STEAM

kinetic model of matter:
determines the properties of each state

ARRANGEMENT OF PARTICLES:

SOLID- closely packed
- regular pattern
- occupies minimum space
results in high density,as there are little intermolecular spaces

-the particles vibrate about fixed positions due to the strong intermolecular bonds
this is why solids have fixed shapes and volumes.

LIQUID- particles are further apart compared to that of solids,but still "packed"
-random pattern
results in high density,as they also have little intermolecular spaces

-the particles are free to move about in the vessel containing it ONLY,they have attractive forces!this is why liquids can take up the shape of its vessel.reason being the particles can only slide pass each other,but not entirely break free.

GAS- very far apart
- randomly arranged
-occupies any given space

results in low densities,it can also be compressed as there are a lot of intermolecular space,thus they have no fixed volume and shape.

-particles move about at high speeds,randomly and have very little attraction between one another.

HOW YOU CAN ROUGHLY REMEBER THIS :
solid(preppy kid)- obeying to parents (high intermoleular force),neat(regular pattern) child,creates almost no trouble(occupies as little space as possible)

liquid(average kid)-obeying to parents,but more subjective on what to obey (have intermolecular forces),not very neat (no regular pattern)

gas (wild child)- out of control ( little intermolecular force),creates a lot of trouble ( occupies a lot of space),very messy (random arrangements)

FINALLY WE'RE DONE WITH THEORYYYYYZXZXZ!VIDEO TIME!

the molecule song!dont worry,theres no weird freaky girl singing here,the songs quite catchy in a GUDD WAY!

molecules in solid cartoon

molecules in liquid

2008-08-31T05:54:00.000-07:00

GRAND OPENING!

click for larger image.

lessons starts soon! :D

longwaytogo,
bye