thermal physics, hot or not

closing ceremony

2008-09-04T21:37:00.000-07:00

i have finally finish my blog for physics

reflection
I have found out that blog is not easy to create. I redid my first post 2 times.on the first try, my picture could not be seen and i could not delete it so no choice but to redo it.on the second try, i accidentally close my window. on the third try, i finally got it right then i realised my post was automatically being saved.

it got better when i got the hang of it. All in all it was quite fun and learned quite alot. i can absorbed better typing info out rather than reading it in tb.

Please comment if you can to help me improve. thank you! school is reopening. hais...

unit 9- thermal properties of matter

2008-09-04T19:43:00.000-07:00

solid to liquid: melting

liquid to gas: boiling or evaporation

gas to liquid: condensation

liquid to solid: freezing or solidification

Melting

when a solid changes to a liquid upon heating is called melting.

At 0 degrees, the molecules in a solid gain enough energy to overcome the force of attraction and becomes less orderly. Now, the molecules can move out of their fixed positions. melting has already taken place.

Solification/ freezing point

- when a liquid changes to a solid is called freezing or the reverse process of melting called solidification.

As temperature decreases. molecules in a liquid lose energy and move closely together. now the molecules cannot move but only vibrate in its fixed positions. freezing has taken place.

Boiling and evaporation

- when a liquid changes into a gas

First, the molecules gain energy and move faster. At 100 degrees, the molecules gain enough energy to overcome the force of attraction increases. they will move further away, boiling has then taken place.

evaporation is also the change of state of liquid to gas. however, they have their differences.

1) boiling takes place only at a certain temp. but evaporation takes place at any time.

2)boiling takes place faster than evaporation

3)boiling takes place thoughout the liquid whereas evaporation takes place only at the surface

4)the temp. wil remain constant for boiling however may vary for evaporation.

5)bubbles are formed during boling but not during evaporation

6)energy souce is needed for boiling whereas evaporation does not.

factors affecting the rate of evaporation

-temperature:high temp will increase the rate of evaporation

- humidity:high humidity causes the rate of evaporation to decrease

- surface area of liquid: the larger the surface area of a liquid, the higher the rate of evaporation

-pressure:to increase the rate of evaporation, a low pressure is needed.

YEAH! ALL COVERED!

going to the next chapter

2008-09-04T03:38:00.000-07:00

Before i start on the next chapter. hear some physics jokes:

Q: What did the thermometer say to a graduated cylinder.

A: You may have graduated but i still have more degrees than you.

Q: At a garage sale, a electron and a proton cost $10 each. How much does a neutron cost?

A: free oF charge ( no charge)

one day hydrogen said,"someone has stolen my electron! i am positive." then oxygen said,"Oh i thought you are just being negative again."

haha. funny. thats all

chapter 8- transfer of thermal energy.

basical this chapter is all about convection and conduction and radiation. the textbook is long winded again so i will summarise what i have learnt.

CONDUCTION

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

Thermal energy is transferred from a region of higher temp. to a lower temp. but the time interval that it is transferred varies on the type of medium being used.

thermal energy is transferred faster in a good conductor (eg. wood) but slower in a poorer conductor( insulator).

this reminds me of a joke. one day a conductor lost his baton hence uses a sword to conduct. during practice, a player was constanly playing out of tune and the conductor got very angry and threw the sword at the player. he killed the player and was sentence to death through a electric chair but survived. the law states that if a man is not dead by the electric chair after 3 times of shocking, he can be released. and one day, the conductor lost his baton again and the same thing happen and still survived the electric chair. Why is this so? it is because he was a bad conductor.

haha funny.

CONVECTION

DEFINATION: Convection is the transfer of thermal energy by means of currents in a fluid

the arrows stated are the convection currents.

Hot air rises, cool air sinks

in this picture, the sun heats the air on the ground of the atmosphere, the hot air(red arrow) rises as air travels from a region of low pressure(hotter)to a region of high pressure(cooler).then the upper part of the atmosphere becomes cool and sinks. this is known as convection.

RADIATION

DEFINATION: Radiation is the continual emission of in farared waves from the surface of all bodies, transmitted without the aid of a medium.

i just went to youtube and found that handphones has high radiation and can cause cancer. i think i will use less of it now.

ALL COVERED!

particles everywhere

2008-09-04T03:12:00.000-07:00

All matter has particles.

the textbook was so long winded so i have summarised the whole table of the arrangement and movemant of particles.

IN SOLID: Particles in this state are in neat rows, little space between them . they do not move around but only vibrate in their fixed position.

IN LIQUID: In this state, the arrangement of particles are the same as the solid state. however, it is untidy and can move freely in the liquid.

IN GAS: the particles are completely opposite of the particles in solid, far apart, move freely, and has lots of space in between each other.

reflection on this chapter:

i feel that i am doing more of chemistry than phisics at first, however, i realised they are both different. chemistry is like essays of answers. physics is more of understanding than memorising.

Physics is all around us.

my first physics post

2008-09-04T02:55:00.000-07:00

My first physics blog Wow. my first time blogging. i had a study group toay and started a new topic for physics: chapter 7-kinetic model of matter. the textbook was so boring, so i have decided to make up my own story.

it started with water....

at room temperature, it was heavy and soft. it took the shape of anything that has a shape. this is known as the LIQUID state.

During summer, where temperatures are above 30 degrees,it became light, invisible known as the GASEOUS state.

When winter came it was hard and heavy and temperature was below 0 degress. this is known as the SOLID state.

since then water has been changing its state.

THE END.