Solely For Physics

Temperature and Internal Energy

2008-09-05T00:30:00.000-07:00

Internal energy is defined as the random, disordered motion of molecules. A room temperature glass of water sitting sitting on a table has no apparent energy, either potential or kinetic. However, on the microscopic scale it is a seething mass of high speed molecules traveling at hundreds of meters per second. If the water were tossed across the room, this microscopic energy would not necessarily be changed when we superimpose an ordered large scale motion on the water as a whole.
"U" is the most common symbol used for internal energy.

Temperature is the degree of hotness or coldness of a body or environment. It is also a measure of the average kinetic energy of the particles in a sample of matter, expressed in terms of units or degrees designated on a standard scale.

The changes of state can be summarised in this slide show:
http://www.slideshare.net/meenng/changes-of-state

Transfer of Thermal Energy

2008-09-04T23:13:00.000-07:00

Convection is the name for a means of heat transfer, as distinguished from conduction and radiation. It is also a term that describes processes affecting the atmosphere, waters, and solid earth. In the atmosphere, hot air rises on convection currents, circulating and creating clouds and winds. Likewise, convection in the hydrosphere circulates water, keeping the temperature gradients of the oceans stable. The term convection generally refers to the movement of fluids, meaning liquids and gases, but in the earth sciences, convection also can be used to describe processes that occur in the solid earth. This geologic convection, as it is known, drives the plate movement that is one of the key aspects of plate tectonics.

Conduction is the transfer of energy through a medium such as heat or electricity through metal, without any apparent change in the medium.

Radiation is energy radiated or transmitted as rays, waves, in the form of particles. Higher doses of radiation may be used to kill cancerous cells.

Kinetic Model of Matter

2008-09-04T22:15:00.000-07:00

Substances such as water can exist in 3 states. These 3 states of matter are Solid, Liquid and Gas. The state of water is dependent on two key factors which are it's tenperature and the atmosphereic pressure. Take water for instance. Ice is water in its solid state. It is formed when temperature hits 0 degree celsius (freezing point of water) or below at atnospheric temperature. However, when water boils at 100 degree celsius and above, it forms water vapour and steam, which is the gaseous state of water. An example of water in its liquid form would be the liquid that we consume, which is usually at room temperature.

A video clip showing the properties of the three states of matter are can be found in this website

http://www.abpischools.org.uk/page/modules/solids-liquids-gases/slg2.cfm?age=Age+Range+7-11&subject=science

The Kinetic model of matter explains the reasons for the properties of matters by examining the arrangment and movement of particles. The irregular motion of smoke particles in the air is called Brownian motion. It occurs only in liquids or gases.

What causes Brownian motion?

It is cause by the bombardment of air molecules on smoke particles in air or water molecules on pollen grains in water.

Above is a picture of Robert Brown, inventer of the Brownian motion.