Atmosphere On The Moon

"Ever wonder why people on the moon appear as they are flying or can jump for a far distance. The reality is that those people can't really fly or jump for miles. They aren't people like superman who have the capability to fly. It is because the moon has a very low gravitational pull. Unlike Earth's where objects stay on the ground due to the gravity. The moon's gravity is so much less then Earths that objects float or can jump high in the air. Thus because the Moon has low gravity it is to weak to hold an atmosphere. So for those who believe that once you are on the moon you have the capability to fly, it's not true. Its the realivily low gravity and the low escape velocity."


Atmosphere On The Moon
Why There Is no Atmosphere on the Moon
Weak Gravity Allows Gas Atoms to Escape so no Air on Small Planets
Buzz Aldrin saw such "magnificent desolation" when he stood on the Moon in July 1969 in part because it lacks an atmosphere. With no air or liquid water to erode the lunar geology, surface features retain their initial ruggedness. This lack of breathing air forced astronauts to wear special sealed spacesuits contributing to the desolation.
To understand why Earth's Moon and other small moons and planets have no atmosphere, it is first necessary to understand a little about gravity and escape velocity.
Gravity on the Moon
Some people think the Moon has no air because there is no gravity on the Moon. This is incorrect. Because the Moon is less massive than Earth the gravitational force on the Moon's surface is weaker than Earth's. There is still gravity on the Moon, but it is too weak to hold a significant atmosphere. Why?
Escape Velocity
When NASA launches a rocket into space, the rocket must reach a minimum speed to break the bonds of Earth's gravity. Rockets not reaching this minimum speed, called the escape velocity, fall back to Earth. Anything traveling at the escape velocity, or faster, can escape into space. Gravity pulls back anything traveling more slowly.
Earth's escape velocity is 11 kilometers/second. With less surface gravity, the Moon's escape velocity is 2.4 kilometers/second. Hence it is much easier to escape into space from the Moon than from Earth.
Heat and Molecular Motions
Gas atoms and molecules don't rest quietly. They move around fairly rapidly in random directions. As the gas temperature increases the average speed of the gas atoms increases. If the speed of a gas atom exceeds the escape velocity, that gas atom can escape into space.
Earth's average temperature is approximately 300 Kelvins. At this temperature the average (technically root mean square) speed of a nitrogen molecule is about 0.5 kilometers/second. Because this speed is much less than Earth's escape velocity Earth holds on to its nitrogen very tightly.
This speed is also less than the escape velocity from the Moon, but it is closer. So gas atoms and molecules can more easily escape from the Moon. To understand why, think about this analogy.
The average height for adult males is somewhere between five and six feet. However there are plenty of men that are either taller or shorter than this range. For example NBA basketball players are often over seven feet tall. However they don't have players over ten feet tall because that is too far above the average.
Escape Velocity and Atmosphere
As a rule of thumb, if the escape velocity is more than ten times the average speed of a particular type of molecule, that type of gas will remain in the atmosphere. Otherwise the molecules will escape over time. On Earth the escape velocity is high enough to hold its atmosphere. Molecules would have to be like the ten foot tall players to escape. On the Moon however the escape speed is low enough that the faster moving atoms can escape. Molecules would have to be like the almost seven foot tall NBA players to escape. So these gas atoms and molecules fly off into space. The Sun heats the remaining gas enough that those atoms and molecules eventually speed up and escape.
Hence less massive moons and planets including the Moon and Mercury have no significant atmospheres. Mars is a little more massive so it has a thin atmosphere. More massive Earth and Venus have significant atmospheres and the very massive gas giant outer planets retain very thick atmospheres.
This article was found from the website (http://physics.suite101.com/article.cfm/why_there_is_no_atmosphere_on_the_moon)

Fireworks

How Fireworks Produce Sounds and Colors
The Science, Physics, and Chemistry Behind Fireworks Displays!
Explosions powered by chemical reactions produce the sounds. Different chemical compounds mixed in the gunpowder produce the colors of fireworks.
Many people enjoy fireworks displays on the first of July, the new year, and other festive holidays. These fireworks displays produce many loud sounds and vibrant colors. How?
How Do Fireworks Make Noise?
When the fuse on a firecracker is lit and burns, it sets off a chemical reaction in the gunpowder. Burning gunpowder releases large amounts of hot gas. If the gunpowder is not confined in any way, the chemical burning reactions release the gas harmlessly, and it does not explode.
If the gunpowder is confined in some way, the gas is not released harmlessly. It explodes. In a bullet, the shell confines the gunpowder so that the high pressure gas released by the chemical burning reactions propels the bullet down the barrel of the gun. In firecrackers or other fireworks, the cardboard shell of the firecracker explodes with a loud popping sound when the chemical burning reaction releases the gas.
What Chemistry and Physics Happens in the Atoms?
The chemical burning reactions in the gunpowder in the fireworks vaporize the gunpowder and the color producing chemicals mixed in with the gunpowder. The hot gas atoms frequently collide with each other in the firework explosion. These collisions push the electrons to higher energy levels, which are higher orbitals, in the atoms. After a short time the electrons jump back down to the lowest energy level, which scientists call the ground state. The electrons must release the extra energy, and they release this energy as light. The color of the light depends on the exact amount of energy released when the electron jumps to the ground state.
Physicists and chemists call the specific colors of light emitted when the electrons jump to lower energy levels the emission line spectrum. Each element has its own unique colors or emission line spectrum. Engineers designing fireworks displays select the chemical elements or compounds that have the right emission line spectrum to produce the desired colors for the display.
Understanding the chemistry and physics of fireworks can increase the enjoyment of a fireworks display.
This article can be found from the website(http://physics.suite101.com/article.cfm/how_fireworks_produce_sounds_and_colors)

"What this articles does not tell you about is what produces the color of fireworks. Doing some research I have learned how fireworkds produce the color they appear to be. Various elements when mixed in with the gun powder in the fire work produce the many colors of the spectrum. This is related to the unit we took on light saying the colors we do see form part of the visible spectrum. For example sodum emits a strong yellowish color when it is burnt. So if a firework appears yellow there is probably sodium in that firework to react with the gun powder. Another example is copper which causes a blue color. So to form any color in a firework there is various chemical elements. This is how a fire appears to be the color it is."

How Magnetic Resonance Imaging (MRI) Works

"Magnetic Resonance Imaging is used in for medical imaging. The procedure for an MRI is the following. Unlike an X ray examination or CT scan MRI does not depend on ionizing radiation. Instead while in the magnet, radio waves redirect the axes of spinning protons. The magnetic field is produced when electric currents are passed through wire coils. Other coils as side from these coils, located in the machine which are plased around the body being imaged recieves and sends radio waves. They then produce signals. A computer picks up these signals and generates a series of images. Thus the image can be studied. This is the basic sturture of how an MRI works. During the examination people must be still and some times asked to hold their breath by the docter. This is all procedures to can an accurate MRI."

How Magnetic Resonance Imaging Works
(Nuclear magnetic resonance imaging provides safe nonintrusive medical diagnostic images of the interior of the human body. How does MRI work?)
One of the many modern diagnostic tools available to medical doctors is magnetic resonance imaging (MRI). MRI scans provide physicians a view of the interior of the patient's body without harming or invading the patient's body in any way. Magnetic resonance imaging is based on the fundamental physics of nuclear magnetic resonance (NMR). How does MRI work?
Nuclear Magnetic Resonance
Nuclear magnetic resonance is an effect that occurs when the nucleus of an atom is placed in a magnetic field. The spinning nucleus in a constant magnetic field wobbles just like a spinning top.
If in addition to the constant magnetic field, there is another magnetic field that varies at the same frequency as the nucleus wobbles, the nucleus will flip back and forth so that the nucleus effectively alternates the direction in which it spins. As the nucleus flips its spin direction, it either absorbs or emits low energy radio waves. Studying these radio waves allows physicists to deduce various properties of the atomic nuclei undergoing NMR.
Safety of NMR and MRI
Nuclear magnetic resonance uses the word nuclear because it involves the nucleus of the atom. It does not however in any way involve any dangerous radiation as people expect from nuclear weapons or other nuclear reactions. The only radiation patients are exposed to by nuclear magnetic resonance imaging is very low energy radio waves. Nuclear magnetic resonance imaging is therefore very safe. The word nuclear was dropped however to allay patient fears. To the average person magnetic resonance imaging sounds less dangerous than nuclear magnetic resonance, and MRI is very safe.
Magnetic Resonance Imaging
Magnetic resonance imaging is a very useful application of NMR. Medical MRI machines are designed to image the nuclei of the hydrogen atoms in the human body. Human bodies contain a high percentage of water, so there are a large number of hydrogen atoms in all human tissue. X-rays image bones well, but image other tissues very poorly. Magnetic resonance imaging therefore provides medical personnel with much better images of the soft tissue in the patient's body than X-rays can provide.

This article was found from the cite (http://physics.suite101.com/article.cfm/how_magnetic_resonance_imaging_mri_works)

Kinetic Energy

Kinetic energy is very simple it is the energy of motion. Objects that contain no motion has kinetic energy. "The faster the body moves the greater the kinetic energy produced. Also the greater the mass and speed of an object the greater the kinetic energy will be" This was found from the website <http://library.thinkquest.org/2745/data/ke.htm>

There are different types of kinetic energy. First there is vibrational which is the energy due to vibrational motion. Secondly there is rotational which is the energy due to rotational motion. Lastly there is translational, the energy due to the motion from one location to another.

Potential Energy
"Potential energy is the same as stored energy. The "stored" energy is held within the gravitational field. When you lift a heavy object you exert energy which later will become kinetic energy when the object is dropped. A lift motor from a roller coaster exerts potential energy when lifting the train to the top of the hill. The higher the train is lifted by the motor the more potential energy is produced; thus, forming a greater amount if kinetic energy when the train is dropped. At the top of the hills the train has a huge amount of potential energy, but it has very little kinetic energy." <http://library.thinkquest.org/2745/data/ke.htm>

Links Related To Kinetic Energy:
http://en.wikipedia.org/wiki/Kinetic_energy
http://www.physicsclassroom.com/Class/energy/U5l1c.cfm

Radiography

Radiography
Radiography is the creation of images by exposing a photographic film or other image receptor to X-rays.
Since X-rays penetrate solid objects, but are weakened by them depending on the object's composition, the resulting picture reveals the internal structure of the object.
The most common use of radiography is in the medical field (where it is known as medical imaging), but veterinarians and engineers also use it..
<http://www.sciencedaily.com/articles/r/radiography.htm>

"Radiography is the use of X rays to view objects. It has been a big advancement in medical viewing. As said above radiography is used in the medical field but it is also used in the industrial field. Radiography was founded the same time X rays were discovered. X rays as we know are electromagnetic waves that do not require a medium to go through. This was learnt during our unit in physics on waves. From researching various cites i have found that radiography started in 1895. Radiography is very simple, all it is is the imaging of objects."

Speed of Sound

Speed of sound
The speed of sound is a term used to describe the speed of sound waves passing through an elastic medium.
The speed varies with the medium employed (for example, sound waves move faster through water than through air), as well as with the properties of the medium, especially temperature.
The term is commonly used to refer specifically to the speed of sound in air.
At sea level, at a temperature of 21 degrees Celsius (70 degrees Fahrenheit) and under normal atmospheric conditions, the speed of sound is 344 m/s (1238 km/h or 770 mph).
The speed varies depending on atmospheric conditions; the most important factor is the temperature.
Humidity has little effect on the speed of sound, nor does air pressure by itself. Air pressure has no effect at all in an ideal gas approximation.
This is because pressure and density both contribute to sound velocity equally, and in an ideal gas the two effects cancel out, leaving only the effect of temperature.Sound usually travels more slowly with greater altitude, due to reduced temperature..
The information provided was found from the website (http://www.sciencedaily.com/articles/s/speed_of_sound.htm)

"The speed of sound is something we learned during our unit on waves. The speed of sound is the disturbance through a medium. The speed of sound is different through different types of objects or substances. For example the speed of sound of air depends among the properties in air. It differs that from the speed of sound through various types of materials such as solids. The speed of sound in solids is greater then that of liquids. The speed of sounds in liquids is greater then that of gases. The speed of sound is one aspect we learned about when we took up our unit on waves. These were the different properties and aspects assosaited with the speed of sound."

Microwaves!!

Microwaves are electromagnetic waves with wavelengths longer than those of terahertz (THz) wavelengths, but relatively short for radio waves.
Microwaves have wavelengths approximately in the range of 30 cm (frequency = 1 GHz) to 1 mm (300 GHz).
However, the boundaries between far infrared light, terahertz radiation, microwaves, and ultra-high-frequency radio waves are fairly arbitrary and are used variously between different fields of study.
A microwave oven works by passing microwave radiation, usually at a frequency of 2450 MHz (a wavelength of 12.24 cm), through the food.
Water, fat, and sugar molecules in the food absorb energy from the microwave beam in a process called dielectric heating.
Many molecules (such as those of water) are electric dipoles, meaning that they have a positive charge at one end and a negative charge at the other, and therefore rotate as they try to align themselves with the alternating electric field induced by the microwave beam.
This molecular movement creates heat as the rotating molecules hit other molecules and put them into motion.
Microwave heating is most efficient on liquid water, and much less so on fats and sugars (which have less molecular dipole moment), and frozen water (where the molecules are not free to rotate)..
The information provided was found from the websited (http://www.sciencedaily.com/articles/matter_energy/physics/)

"As stated in the above article I've learned that microwaves are electromagnetic waves. Electromagnetic waves are waves that do not require a medium to go through. Microwaves are very good at transmitting information from one place to another. This is one used of microwaves. Another used microwaves have are that shorter microwaves are used in remote sensing. An example of this is weather forecasting. The most commom used of microwaves are those of microwave ovens or the kitchen appliance microwaves. The microwave radiation heats the water molecules within food. This results in the heating of your food but not completely baking your food. One interesting fact about microwaves were that they were first discovered in the 1940's."