The sun is the center of the solar system. The sun is the largest object in solar system. It is diameter ia approximately 1,4 million kilometer it consists of hydrogent and helium. The sun is 333.000 times as massive as t


physics lessons for elementary schools, middle schools, high schools

Global Warming

Some plants are often grown in a glasshouse (greenhouse)What is advantage of a greehouse ?

extreme weather in Indonesia

frequent extreme weather in Indonesia, according to climatology meteorology and geophysics, extreme weather

greetings in Happy New Year 2012

Fisika Education : Teaching materials, practice questions and articles Physics for elementary, junior high school, vocational school

Thursday, August 16, 2012

Work Heat and Internal Enegi

a. System and Environment
A system is part of the universe wich becomes the attention of an observation. While the environment is other part of the universe which is separated from the system. Examples of a system we can see in daily life is helium gas cylinder and ga balloon.

If we are only observing the helium gas tube, than the tube becomes the boundary between, the system and its outside emviroment.
Otherwise if we are only observing the balloon, then the surface of the balloon becomes the boundary between the system and its outside environment.

Work is the amount of energy transferred from the system to its environment o vice versa.

Heat is the amount of energy transferred from the system to its environment resulting from the temperature difference.

d.Internal energy
Internal energy is the sum of the kinetic and potential energies of all the atoms or moleculs of substance.

Work                                Heat                          Internal energy

Since it is microscopic, than what we can observe macroscopically is the conversion of the internal energy ΔU of the substance. If the system changes from initial state U1 into final state U2, then the change of internal energy is  :
    ΔU = U2 –U1

Sunday, August 5, 2012

TIDE physics edu

physics in the article today, I elaborated on the tide

A tide is the periodic rice and fall of the sea surface.
Tide result from the gravitational attraction of the moon.

The principal couse of tide is the moon being much nearer to the earth then the sun so that the world’s oceans flow in response to the moon’s pull.

Because the moon moves around the earth, the highest high tide and the lowest high tide can occur.

a. The highest high tide if the Eart, Moon and Sun are in the same line (if seen from North). The highest hige tide is often called luna tide.

b. The lowest high tide accurs if Eart, Moon and Sun make a right angle (90o). the lower high tide is often called a quarter tide.

Friday, August 3, 2012


edu physics now discuss the physics of the LAW OF Reflection
well here is an explanation and drawings, safe learning

There are many examples indicating that light travels in a straight line. The image formed is the same as the object. It indicates that light travels in a straight line.

What happens when the light strikes the surface of an object ?
Part of the light will be reflected. And the other part ill be absorbed by the object ( and converted into heat energy).

For a very shiny object such as a silvered mirror, more than 95 5 of the light is reflected.

If the object is transparent such as glass or water, then most of the light will be transmitted.

Analysis of Reflection

• The normal is imaginary line perpendicular to the mirror surface.
• The angle of incidence is the angle between the incident ray and the normal.
• The angle of reflection is the angle between the reflected ray the normal.

The result of experiment concludes that :
1. The incident ray, the reflected ray and the normal at the point of incidence all lie on the same plane.
2. The angle of incidence i is equal to the angle of reflection r’ or witten as i = r’

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