Tuesday, September 2, 2008
DONE Well, i completed my physics posts! :D YAY! (: anyways, not sure why got so many ppl viewed my blog, at one go.. 11 online cybers.-.- i got a screenshot to prove it too. hahas! ok, be original! dont come coping from my blog. lols. Yup, started on the 31Aug and ended today, 2sept. hee. Posted at 6:16 PM
Chapter 9 Thermal Properties Of Matter. Internal energy - Particles in a matter(solid, liquid or gas) posses energy called internal energy. - Comprises of 2 components: 1. Kinetic energy 2. Potential energy The kinetic component - Higher the temperature, the more vigorously the particles move. • Kinetic energy is due to their movement instead of vibrations. The potential component - Due to the stretching and compressing of the intermolecular bonds as the particles vibrate. - Amount of potential energy stored in the bonds depends on the force between the particles and how far apart the particles are. • An increase in temperature leads to an increase in the kinetic component of the internal energy. Melting Heating Curve. • When a solid changes to a liquid upon heating. • Pure substances –melting occurs at a definite or constant temperature. - The temperature goes up the longer the heating continues. However, there are two horizontal flat parts to the graph. These happen when there is a change of state. • The first change of state is melting (changing from a solid to a liquid). The temperature stays the same while a substance melts. • The second change of state is boiling (changing from a liquid to a gas). The temperature stays the same while a substance boils. During melting - Heat is absorbed to break the attractive force between the particles - Allows them to break free from their fixed positions and are able to move about. During boiling - Heat is absorbed to break the attractive force between the particles - Allows them to move freely and randomly in all directions. Solidification. - Reverse process of melting - A pure substance will sodify or freeze at a temperature equal to its melting point. Cooling Curve. During condensation -The motion of particles becomes less vigorous in order to form the attractive force between the particles when a gas changes into a liquid. During freezing (solidification) -Strong attractive force can be formed between the particles in order to be arranged in a regular pattern at their fixed positions. Condensation • A process whereby vapour changes into liquid at the same constant temperature. Heat is given out during condensation. • During condesation, the temperature remains constant at the condensation point. Thermal energy is released by the substance. Boiling and Evaporation • Boiling is a process in which a liquid changes into a gas at the boiling point of the liquid. • Evaporation is a process in which a liquid changes into a gas temperatures below the boiling point of the liquid. Difference between boiling and evaporation. Boiling - Occurs at constant temperature - Happens within the liquid - Bubbles produced - Rate of process: Fast Evaporation - Occurs at any temperature - Only the surface of the liquid involved - No bubbles - Rate of process: Slow Evaporation • A cooling process • Evaporation of a liquid is due to the molecules at the surface with energy greater than the average kinetic energy escaping from the rest of the liquid. Factors affecting the rate of evaporation. 1. Temperature - Higher the temperature of the liquid, the higher the rate of evaporation. 2. Humidity of the surrounding air - Lower the humidity of the surrounding air, the higher the rate of evaporation. 3. Surface area of the liquid - Greater the surface area of the liquid, the higher the rate of evaporation. 4. Movement of air 5. Pressure - Lower the pressure in the surroundings, the higher the rate of evaporation. 6. Boiling point of a liquid >Eureka! Episode 18 - Evaporation and Condensation, Video-YouTube Posted at 4:07 AM
Monday, September 1, 2008
Chapter 8 Transfer Of Thermal Energy.
•Conduction is a point-to-point (by contact) transfer of energy. Molecules that are energetic impart energy to those nearby that are less energetic, thus increasing their temperature.
- A radiator in a room heats up the room by convection. - Hot water system uses the concept of convection. • With a convection circulation system set up, the hot water storage tank gradually becomes filled with hot water from the top downwards. • When hot water is run off, an equal volume from the cold supply tank enters the hot storage tank at the bottom. The whole system is thus kept constantly full of water and no air can enter. - Coastal breeze is an example of natural convection. Applications of radiation - Green house effect • A warm environment. • Short infrared radiation from sun passes through the glass panels of a green house, and is absorbed by the plants and soil inside. • This radiation is reflected by the glass panels • Temperature inside the green house increases until it reaches a thermal equilibrium suitable for plant growth. - Vacuum flask • Is a container that is used to keep liquids warm for a longer period of time. • Its design has important features to reduce heat transfer from inside the flask to the surroundings through conduction, convection and radiation. Plastic cap • Made of material which is an insulator - prevents heat loss by convection because hot air cannot escape Trapped air • air is a very poor conductor of heat - reduces heat lose by conduction Vacuum • no particles in vacuum - reduces heat loss by conduction and convection as both processes need particles to transfer heat. Thin silvered glass walls • silvered surface is a good reflector of heat - it reflects heat back inside the flask, reduces heat loss by radiation This picture somewhat sums up on chapter 8, >Easy to Understand; web on Conduction, Convection and Radiation. Posted at 1:21 AM
Sunday, August 31, 2008
Chapter 7 Kinetic Model Of Matter.
Why does liquid have a definite volume but not a fixed shape?
• This is because as temperature increase, a larger amount of thermal energy is converted to kinetic energy of the air molecules, causing the molecules to move faster. Posted at 11:06 PM
Wednesday, August 27, 2008
Thermal Physics Hmm, my Thermal Physics blog officially opened today. lols. well, will get it done soon...(: in the process of doing it... Posted at 8:23 PM |
Thermal Physics™ Chapter 7, 8 , 9 of the Physics Textbook. Protagonist. SHERYL PLMGS(S) 3B1 Blogged opened on, 27 August 2008. Tagboard. hits Online Cyber(s). Quick Links. ^Chapter 7 ^Chapter 8 ^Chapter 9 Videos. - YouTube >States On Matter Eureka! >Episode 16 - Molecules in Solids >Episode 17 - Molecules in Liquid >Episode 21 - Temperature vs. Heat >Episode 24 - Conduction >Episode 27 - Convection >Episode 29 - Radiation Waves >Episode 18 - Evaporation and Condensation Easy to Understand web on Chapter 8 Links. 3B1'2008 Amanda Liew Brenda Lee Huang Chara Cherlyn Christina Xin Yan Wen Shi Clarice Jolene Ek Germaine Clara Isabel Joann Leah Amanda Lim Zi Ai Maureen Mii Wei Melissa Li Ying Wan Leng Neo yun Samantha Ang En Yin Sheena ->Sheryl< Shobana Stephanie Jesslyn Valerie Yu Xian Ying Ching Qing Hui Cassandra Vanessar Jia Yee Xiao Wei Kai Jing Joaquim Eileen ErnHuei Elizabeth Tan Credits. ! Physics Textbook ! Yahoo/MSN Search Engine -- Images ! YouTube |