The Crust of the Earth

Introduction to crust of earth:

In the ancient time when the earth was formed it was very cold. This earth is called as the primitive earth. As more and more planetesimals collided with the primitive earth and stuck to it, their kinetic energy got converted into heat. Radioactive disintegration of the elements, such as Uranium, Thorium etc and contraction of earth due to gravitational force also heated the primitive earth. This heating of primitive earth gradually raises its temperature and the primitive earth melted. The molten material of the earth then began to reorganize into layered structure under the influence of gravity. During the formation of layered structure the lighter molten rose up to the surface to make the earth’s crust.


Description on crust of the earth:


There are three major layers of earth out of which the uppermost layer is called the crust of the earth. The thickness of the crust of earth varies from place to place. It lies between 35 km to 60 km under continents and about 10 km under oceans. The ocean crust is different from the continental crust. The ocean crust is made up of basalt, diabase and gabbro. The continental and the ocean crust float on the second layer of earth called mantle.   The crust of the earth generally composed of lighter elements. About 75% of the earth’s crust is covered with water. The crust of the earth is composed of igneous, metamorphic and sedimentary rocks. The crust of the earth occupies the earth’s volume by less than 1%. The average density for the upper crust lies between 2.7 gram per cubic centimeter and 2.74 gram per cubic centimeter. The average density of the lower crust lies between 3.0 gram per cubic centimeter and 3.25 gram per cubic centimeter. The temperature of the crust of the earth increases with the depth. The temperature of the crust of the earth lies between 200° C to 400° C.  The temperature of the earth’s crust increases by 30° C for every kilometer

Understanding specific heat equation is always challenging for me but thanks to all science help websites to help me out.

Conclusion on crust of the earth:


Most of the rocks in the crust of the earth formed before 2.5 billion years ago. The interior crust of the earth makes up lithosphere. The lithosphere is converted into tectonic plates.

Laser Cutting Process

Introduction to laser cutting process:

Laser which stands for Light amplification by stimulated emission of radiation.When electromagnetic radiation or some times visible radiations  released by the stimulated emission then this is known as Lasers.Electrons present in the elements can change their state in order to attain stability.When any energy is supplied then electrons are excited to higher states,but at the higher states these are not so stable so it jumps down by releasing some energy.These energy comes under certain range .It can be in the electromagnetic range,visible range or may be in some other range of the spectrum.Laser is a monochromatic and short wavelength rays.These rays have high frequency. Is this topic Definition Kinetic Energy hard for you? Watch out for my coming posts.

Laser beams are very useful in many fields.Laser cutting is also a field where lasers are used to cut the materials.Lasers are very high power beams when it is subjected to the materials then material melts,vaporises or burns,or it is blown away by the high pressure beams.As compared to the mechanical cutting this process of cutting is very effective and accurate.Some times materials are very hard to cut by using normal mechanical methods,so in these cases laser cutting  helps and it makes the cutting very easy and simple.

Types of Laser

There are mainly three types of laser cutting device is used depending upon the material used for the production of lasers.These materials are.

1)Carbon Dioxide

2)Neodymium

3)Neodymium yttrium Aluminium garnet

These different lasers are used in different applications.These are used for cutting,trimming,scribing.engraving etc.To produce the laser beams the lasing materials are stimulated ,then the generated beam is reflected so many times internally by using mirrors till it gains high  energy  to come out as monochromatic beams.



Different Methods of Cutting by Laser

By using laser cutting of material can be done in various ways.The high energy of the beam is mainly used to cut the material.Some of the methods are described below

By vaporising-in this method the material is heated to its boiling point to obtain a gap.

Thermal stress cutting-This method is used for the brittle material .When Brittle material is subjected to high heat then it results in crack.

melt and blow-In this method first the material is melt and then it is blown by high pressure beams.

By cold cutting

Scribing

Conservation of Kinetic Energy

Introduction to Conservation of kinetic Energy:

Have you ever observed a ball when thrown vertically upward with certain force? It goes to a certain height and comes back to the ground when it strikes the ground it bounces back in upward direction once again. Do you know what different forms of energy are involved here and what energy conversion is going on in this motion? Before understanding this, let us try to understand what Conservation of Energy is.

For an isolated system, the total amount of energy remains conserved. In other words we can say that energy can neither be created nor destroyed, it can only be changed from one form to the other. Conservation of energy tells that the total amount of energy remains unchanged. However, during a process or activity one form of energy may get changed to the other form, but if you calculate the total amount of energy, it will remain conserved.

Conservation of Energy when Ball Going Up

For an example If a is ball thrown vertically upward. Using our muscle energy, we provide some kinetic energy to ball and ball starts moving with this kinetic energy in upward direction. As the ball goes up its kinetic energy starts converting into potential energy. As a result the kinetic energy of the ball start decreasing and potential energy of the ball starts increasing. Due to decrease in kinetic energy, the velocity of the keeps on decreasing and finally at one point it becomes zero. This is the highest point up to which ball can go. At this point the total kinetic energy of the ball has converted into potential energy.
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Thus at highest point, ball has no kinetic energy and highest potential energy. It is interesting to know that the potential energy as this point is equal to initial kinetic energy of the ball. This is as per the conservation of energy because kinetic energy is converted into potential energy but total amount of energy remains same.

Conservation of Energy when Ball Falls Down

Now ball starts falling down with this potential energy and as it falls down under gravity, its potential energy starts converting into kinetic energy. As a result the potential energy decreases and kinetic energy increases and velocity of the ball goes on increasing. The moment when ball strikes the ground, all its potential energy is converted into kinetic energy and once again due to conservation of energy, this energy is equal to the potential energy at the top as well as to the initial kinetic energy.