Wow Physics! O:

2008-09-07T00:09:00.002+08:00

I love Physics babeh.

Hahah ohkay.I was so happy that I finished the blog kay!
Anyway,It really tested my patience very badly.
Especially I have so many picture posts,I have to scroll
Backspace, drag and enter. It's like O:

Omg that two days of mugging was really O:
And Idk hahah frustrating and tiring

But I must admit that I did learn something I guess?
Hhaha it was rather useful lah (!)

Oh man,I've yet to finish my holiday homework
& there's school tmr! D:
Yeah get that,Tmr.

Tag replies:

Limpeh: Hah thank you. There's a video? It's not lah You're suppose to go to the web and play with it. Everyone could get there! Haha your computer lousy lah :D Ah,yes Hahah.

2008-09-06T03:26:00.002+08:00

Oh hey.

Look at the time now D:
Hahha I'll do the tag replies tmr.
No wait
Later I meant,Not tmr(:

I'm too tired and lazy to do it now
It's already 3.28 D:
I'll do the reflections tmr or something.
NO WAIT.
NOT TMR,
Later(:

Kay goodnight.

HOORAY! It's over :D

2008-09-05T23:48:00.000+08:00

Oh no I know I'm running short of time but still!

Last Chapter already Omg (Yawn big time O: )
Just abit more lah kay :D

Continue from Chapter 9..

EVAPORATION

Evaporation is the change of state from liquid to gas
Evaporation can also occur at any temperature!

Differnce between boiling and evaporation

Boiling

Occurs at a fixed temperature
Quick process
Takes plave throughout the liquid
Bubbles are formed in the liquid
Tempertaure remains constant
Thermal energy supplied by an evergy source

Evaporation

Occurs at any temperature
Slow process
Takes place only at the liquid surface
No bubbles are formed in the liquid
Temperature may change
Thermal energy supplied by the surroundings

Now you see the difference? :D

Evaporation causes cooling!

OMG LOOK (:

When you step out of the swimming pool,your body will feel cold.
Have you ever wondered why? (:

Thermal Energy from your body helps the water on the skin to evaporate.When the water evaporates,it takes away thermal energy from the surface of your skin.Hence you'll feel cold.

NOW you know why :D

HOW DOES EVAPORATION OCCUR?

Evaporation occurs only at the surface of the liquid
Energetic molecules escape,carrying thermal energy away
Some molecules rebound into liquiddue to collision with the air molecules or other escaping molecules
Less energetic molecules are then left behind in the ether.

APPLICATIONS OF EVAPORATION (!!!)

Puddles of water WILL dry up after awhile

Refrigerators uses the principles of condensation and evaporation in the cooling process to help keep its contents cold

FACTORS AFFECTING THE RATE OF EVAPORATION

1. Temperature

Raising the temperature of the liquid will increase the rate of evaporation.

2.Humidity of the surrounding air

The air is humid when there is alot of water vapour present in the air.
Rate of evaporation decreases with increasing humidity
Wet clothes do not dry easily if the surrounding air is damp

Wet floors take longer to dry on humid days

3. Surface area of the liquid

More exposed surface area,rate of evaporation increases
This explains why wet clothes should be spread out for drying to expose to the maximum possible surface area for evaporation to take place.

4.Movement of air

WE cool down faster in moving air than in still air.

The moving air from the hair dryer removes the molecules of the liquid as soon as they escape from the surface of your hair.
Hence the rate of evaporation increases when the surrounding air is moving.

5.Pressure

Reducing the atmospheric pressure increases the rate of evaporation

6.Boiling point of the liquid

Liquids with lower boiling points will evaporate faster.

_________________________________________

OMG YES!
I'M DONE! (:

Goodbye!
I LOVE Thermal Physics :D

1st post for Chapter 9 D:

2008-09-05T23:27:00.007+08:00

YAY YAY YIPPI YAY

Hello everybody,We're going to start on chapter 9

AND IT'S GOING TO BE THE LAST CHAPTER!

Kay lets not waste anymore time,and start on work!(:

CHAPTER 9!

THERMAL PROPERTIES OF MATTER(!!)

Process of heating a beaker of water!

We are applying thermal energy from the Bunsen flame to the water
This thermal energy supplied to the water leads to a gain in the INTERNAL ENERGY of the water molecules

Microwave!

A microwave oven raises the internal energy of food by making water molecules in the food vibrate VIGOROUSLY O:

Slinky! ( So fun right)

Potential energy is stored in the slinky as it is stretched or compressed!

MELTING AND SOLIDFICATION!

Melting is when a solid changes to a liquid upon heating
Melting occurs at a definte or constant temperature for pure substances

HOW DOES A SOLID MELT

The molecules in the solid are held by strong intermolecular bonds
The bonds have to be broken to melt
Once it is broken,the molecules can now move out of their fixed position
And therefore,A change of state from solid to liquid has occured
Hence there is no change in temperature during melting

SOLIDIFICATION!

Solidification is a reverse process of melting
Changing a LIQUID ->SOLID

Freezing point!

Water freezes to form ice at 0 degrees.
Therefore this temperature of 0 degrees is called the melting point of the water.

BOILING AND CONDENSATION

Boiling is

A pure liquid heated and changes to a vapour

HOW ABOUT CONDENSATION?

Condensation is

A reverse of boiling
Changes a state from vapour to liquid
Thermal Energy is given out during condensation

HOW DOES A LIQUID BOIL?

The thermal energy is used to do work to seperate the molecules as well as push back to the surrounding atmosphere.The molecules are now much further apart with negligible intermolecular forces of attraction btween them.

And hence when this happens boiling has taken place (YAY)

Watch when you're free(!!)

2008-09-05T23:10:00.002+08:00

Chapter 7

Omg HAHAHA this video's damn retarded
Please don't stop watching just because the starting is SILLY.
Just watch the whole thing(It's related to physics for nuts!)

This one is more about Solid,liquid&gas itself(:

Chapter 8

CONDUCTION CONVECTION RADIATION

Part 1

This will take quite long to load
But It's worth the wait afterall :D

Part 2

Part 3

Last post on Chapter 8 (!)

2008-09-05T22:39:00.010+08:00

Yet again,Still on Chapter 8
But finishing soon already! :D

Common applications of convection (!)

1. Electric Kettles

The heating coil is always placed at the bottom of the kettle to aid transfer of thermal energy in water by CONVECTION.

2. Household hot water systems

The household hot water system is designed based on the CONVECTION in liquids.

3.Air Conditioners

Air conditioners is always installed near to the ceiling of a room to facilitate setting up of CONVECTION currents.
An air conditioner releases cool dry air into the room.As cool air is denser,it will tend to sink.The warm air below,being less dense,will rise and is drawn into the air conditioner where it is cooled.

Easy? :D

4.Refrigerators

They work the same way as air conditioners.

Freezing unit is usually placed at the top to cool the air and facilitate the setting up of CONVECTION currents.It will help cool the contents inside(:

Common applications of radiation (!!)

1. Teapots ( SHINY TEAPOTS :D )

Shiny surfaces are BAD emitters of radiation!
They can keep tea warm and help to keep cold liquids cool for a longer time than the black teapots(: SO BUY SHINY ONES NEXT TIME! :D

2. The greenhouse O:

Greenhouse is used in cold climates to help plants grow better just by trapping heat (Wow)
Infrared radiation from the sun pass through the glass roof of the greenhouse and therefore helps to warm up the soil and plants in the greenhouse.
As the contents get warmed up,they'll start to emit infrared radiation
The amount of infrared radiation in the greenhouse builds up over time,and hence,causes the temperature in the greenhouse to increase O:

3.Vacuum flasks!

THEY^ are designed to keep liquids hot by minimising heat loss in 4 O: Possible ways.

CONDUCTION(!)
CONVECTION(!!)
RADIATION(!!!)
EVAPORATION(!!!!)

The stopper is usually made of plastic which is a poor conductor of heat ( GOOD! )
Conduction through the trapped air above the liquid is minimal
CONDUCTION & CONVECTION through the sides of the flask are prevented by the vacuum between the walls of the flask.

____________________________________

ZOMG ZOMG ZOMG.
I FINISHED CHAPTER 8!
CLAPCLAPCLAP O:

Kay I have 35 mins to do CHAPTER 9 ZOMG.
I don't wish to do shoddy work,I'LL DO NOW
Bye

2nd post on Chapter 8 O:

2008-09-05T21:14:00.010+08:00

Still on Chapter 8 (!!) Omg why so long D:

APPLICATIONS OF THERMAL ENERGY TRANSFER!(:

Spare you from words first yeah(:

Take a look at the pictures.

Cooking Utensils:

Kettles:

Soldering Iron Rods:

Heat exchangers:

They all have something in Common! And that is they are

USES OF GOOD CONDUCTORS OF HEAT ( CLAPCLAP)

Somemore peektures? :D

Sure(!!)

Handles of appliances and Utensils:

Table Mats:

Sawdust:

Wooden ladies

Woollen clothes:

Fibreglass,felt and expanded polystyrene foam:

A slide made of fibreglass ^

They are all:

USES OF BAD CONDUCTORS OF HEAT (Insulators)

Don't look down on them!

They are very useful if we want to minimise loss of thermal energy,or prevent thermal energy from being transferred quickly (Woah)

WOW (YAY!) So many pictures right.

Man my hands are tired from backspacing and scrolling ):

1st post on Chapter 8

2008-09-05T15:45:00.013+08:00

CHAPTER 8 Oh WOW D:

Transfering of Thermal Energy

TRY THIS OUT (!!!)

Your hand will feel cold when immersed into the Blue basin.
While your left hand will feel warm in the Red basin.
However when your both hands are placed in the Pink basin,
(which is kept at body temperature)You will feel neither hot or cold

Obviously from that,we can feel if something is hot or cold (:
Therefore shows that Thermal Energy

Only transferred when there is a difference in tempertaure
Always flows from a region of higher temperature to a region of lower temperature

How is Thermal Energy transferred (?)

THREE PROCESSES!

Radiation
Conduction
Convection

Red Crazy Cow (Oh?)

___________________________________

Radiation

What is radiation?

It is the continual emission of infared waves from the surface of all bodies,transmitted without the aid of a medium.

Unlike Conduction & Convection

Radiation DOES NOT require a medium for energy transfer
Radiation can take place in a vacuum

Example(!)
Thermal Energy from the Sun reaches the earth by the process of Radiation!

Conduction or Convection is not possible because of the vacuum between the Sun and the Earth.

Thermal Energy from the infrared waves is call RADIENT WAVES.
Actually,all objects emit some radient heat.
The hotter the object,the greater the amount of radient heat emitted! Hah It's as simple as that(:

Absorption of infrared radiation

Infrared radiation

Is absorbed by all objects & surfaces.
Absorption of radient heat causes a temperature rise

Emission of infrared radiation

Infrared radiation

Is emitted by all objects and surface
This emission causes the temperature of the objects to fall
A good emitter of radient heat is also a good absorber of radient heat.Conversely,a poor emitter of radient heat is also a poor absorber of radient heat.

Factors affecting rate of infrared radiation

Again,it depends on three factors.

1. Colour & texture of the surface

Dull,black surface are better absorbers of infrared radiation.
They are better than shiny & white surfaces
Dull surfaces are better emitters of infrared radiation

2.Surface Temperature

The higher the temperature of the surface of the object relative to the surrounding temperature,the higher the rate of infrared radiation(:

3.Surface Area

Compare two objects with same mass & material
The object with larger surface area will emit infrared radiation at a higher rate than the object with smaller surface area.

____________________________________

Conduction

Conduction is the process of thermal energy transfer without any flow of the material medium.

Here's an exampple:

Place three small pieces of candle wax on the piece of thick metal wire
Hold one end to the wire and the other end to the flame of a burner
The wax will melt beginning with the piece nearest to the flame working down to the farthest piece.
This demonstrates that the heat is traveling through the length of the wire.

Conduction in liquids and gases

In liquid & gas,

Thermal energy can also be conducted
Process of conduction is inefficient
Particles are spaced further apart than those in solid
Collisions between particles are less frequent

Example:

This experiment shows that the rate of thermal energy transfer by conduction from the water at the top to the tottom of the test tube is extremely slow.And therefore shows that water is a poor conductor of heat.

___________________________________

Convection

What is Convection?

Convection is the transfer of thermal energy by means of currents in a fluid (Liquid&Gases)

How does convection work?

Water at the bottom of the flask is heated,It will expand.
The expanded water starts to rise as it is less dense than the surrounding water
The cooler regions of the water in the upper part of the flask,being denser, It starts to sink.

Hot air rises,while cool air sinks.

Convection currents occur only in fluids such as liquids and gases but not in solids.

A convection current is the movement of fluid caused by the changes in density in various parts of the fluid.

In some situations,all three

Radiation
Conduction
Convection

Happens at the same time like this -

Wow,that's me!

2008-09-04T23:40:00.011+08:00

CHAPTER 7

Hey kids (Hhahah!)

So.. We're going to talk about,

THE STATES OF MATTER (!!)
Oh we did this for chemistry also,didn't we? (:

Matter is anything that takes up SPACE and has MASS.

Matter is all around you. Your computer is matter. Air is matter. Water is matter. You are matter. In fact, you are made of the 3 major states of matter; solid, liquid and gas!
Substances (like WATER) can also exist in three states of matter,solid,liquid,gas.

Solid

Fixed shape and volume
Normally hard & rigid
High density
Incompressible

Liquid

Fixed volume
Does not have a fixed shape
High density
Incompressible

Gas

No fixed shape/volume
Low density
Compressible

Arrangement of particles & Movement of particles

Solid

They are closely packed together
Very little space between the particles
Therefore resulting in HIGH Density
The particles vibrate about fixed positions only
They are held together in position by strong intermolecular bonds

Liquid

Randomly arranged
Paticles have more space in between compared to solid
Therefore,resulting in having Relatively High Densities
The particles are free to move
Have attractive forces between them
Therefore explains why liquid have fixed volumes

Gas

The particles are far apart
Randomly arranged
Take up any available space
Therefore resulting in LOW densities
Paticles have very LITTLE attraction
They move about randomly at HIGH speeds
Therefore,have no fixed volume and shape
HIGHLY compressible

Kay let's take a break from all these WORDS.Zomg!

Here are some video's to summarise for you
The states of matter! (It's very interesting,Haha I promise!)
It'll take 1-2 minutes to load
BUT good things are worth the wait (!!!)
Enjoy yourself yes (Watching those retarded things(?) Hah)

LOOK HERE! NOW..

CLICK HERE O:

CLICK HERE (!!!)

(Take a look at the graph below while you increase heat)

Phew,Hahah a bit more to go!
And CHAPTER 7 will come to an end :D

BROWNIAN MOTION!

What's brownian motion? (:

It's a random motion of Smoke particles in the AIR!
It's a way to observe that the tiny particles (that cannot be seen by naked eyes) exist and are always in continuous motion.
Brownian motion ONLY occur in fluids,A fluid is any substance that can flow or has particles that can move freely,like gas or liquids.

LOOK HERE.

So cool right C:

Smoke particles move irregularly
They are bombarded by air molecules
The smoke particles are much LARGER than air molecules
Therefore continually bombarded unevenly
Results in irregular movement of smoke particles

Look at the molecules!^

Also,here's an example of brownian motion on dust

Microscopic particles in a liquid or gas (e.g. a piece of dust) contiually move randomly in a zigzag fashion. This is called Brownian motion.

YAY!

CLICK HERE (play with it!)
You'll understand better how brownian motion works!(:
Have fun hur!

HOORAY! CHAPTER 7 IS DONE!
Do you understand? :D
At least a bit rightt (:

2008-09-04T22:17:00.000+08:00

Ng Wanleng

Promise to start blogging tmr morning!(:
You know she's very sad that it's still blank D:
BUT it'll be up soon (!!!)