Sunday, July 15, 2007

Facts About the Moon

The Moon is the only natural satellite of Earth.  The Moon, has been known since time immemorial. It is the second brightest object in the sky after the Sun. As the Moon orbits around the Earth. I takes approximately one month to complete one rotation. The Moon is the only celestial body that humans have travelled to and landed on and have brought samples.  The Soviet spacecraft Luna 2 was the first one to land on the moon on the July 20, 1959.  Neil Armstrong became the first man to step onto the surface of the Moon On July 20, 1969.

By simply viewing through the naked eye one can see two major types of terrain: relatively bright highlands and darker plains. The Moon has no atmosphere. The lunar sky is always dark as the diffraction of light requires an atmosphere. Various samples obtained reveal that there are three types of Terrain on the moon, the Regolith, the maria, and the Terrae. 'Regolith is the outermost part, the relatively bright, heavily cratered highlands are called "Terrae" and the dark, lightly cratered  is called "Maria".

Meteorite impacts on the moon brought a variety of "exotic" rocks to the Moon.  The samples obtained produced many different rock types for study. The underlying crust was also thinned and cracked due to the impacts. Due to the lack atmosphere nor any water, the components in the soils do not weather chemically as they would on Earth. Rocks more than 4 billion years old still exist there, yielding information about the early history of the solar system that is unavailable on Earth.

The gravitational forces between the Earth and the Moon cause some interesting effects. The most obvious is the tides. The Moon's gravitational attraction is stronger on the side of the Earth nearest to the Moon and weaker on the opposite side. Since the Earth, and particularly the oceans, is not perfectly rigid it is stretched out along the line toward the Moon. From our perspective on the Earth's surface we see two small bulges, one in the direction of the Moon and one directly opposite. The effect is much stronger in the ocean water than in the solid crust so the water bulges are higher.

The Moon has no global magnetic field. But some of its surface rocks exhibit magnetism which indicates there could have been a global magnetic field early in the Moon's history. The Moon's surface is completely exposed to the solar wind and many ions form the solar wind have become embedded in the moon's Regolith.

Friday, July 06, 2007

Newton's Laws of Motion

Newton's laws of motion are three physical laws. These laws provide relationships between the forces acting on a body and the motion of the body.Newton's laws were first published together in his work Philosophiae Naturalis Principia Mathematica (1687). The laws form the basis for classical mechanics. Newton used them to explain many results concerning the motion of physical objects.

Newton's First Law of Motion:
Every object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it.

Newton's Second Law of Motion:
The relationship between an object's mass m, its acceleration a, and the applied force F is F = ma. Acceleration and force are vectors (as indicated by their symbols being displayed in slant bold font); in this law the direction of the force vector is the same as the direction of the acceleration vector.

Newton's Third Law of Motion:
For every action there is an equal and opposite reaction.

The first law is termed as the "Law of Inertia".  The second law aid in quantitative calculations of dynamics.  This law explains the velocity chnages that happen when a force is applied.  The third law exemplifies by what happens when we bounce a rubber ball on the ground it pushes back itself witht he same force in the opposite direction.