Friday, May 31

Physical Weathering of Rocks

Introduction to Weathering:

Weathering is a process where the earth’s rocks, soil, and mineral break down due to the direct contact with the planet’s atmosphere. The weathering occurs due to no movement, this is called as ‘situ’. The man-made structures also face weathering problems due to atmospheric exposure. Weathering is of two types, physical weathering, here the breakdown of the rocks and soil is due to the atmospheric conditions such as ice, water, heat, and pressure.Another type is chemical weathering, it is a process where the earth’s rocks and soil breaks down due to the effect of the earth’s atmospheric chemical directly on them.Please express your views of this topic Internal Energy Equation by commenting on blog.

Physical Weathering:

In physical weathering abrasion is the primary process, the physical and chemical process are inter related, as the cracks created by the physical process are increased in the surface area by the chemical reactions on it.

Type in physical weathering:

Thermal stress: Thermal stress weathering is process which causes due to the expansion and contraction of the rocks as a result of temperature change. This is more common in the desert and the regions where the temperature is higher in the day time and cooler at the night.
Frost weathering: This type of weathering is common in the regions where the temperature is nearer to or around the freezing point of water. Here the soil or rocks get cracked due to the low temperatures
Pressure release: Here the materials which is not necessarily rocks having a heavy mass are removed or it is also known as unloading of overlaying materials. This is done by some erosion or other processes. As these over laying materials are heavy they create pressure on the underlying materials.
Hydraulic action: This action occurs in the rock face when the water rushes rapidly in the cracks. At the bottom of the crack the water and a layer of air gets trapped, this causes explosion when the wave retreats which results in crack widening.

5 Forms of Energy

Energy represents itself in various forms. For a physics student it is required that he must be aware of all these forms. In this article we shall discuss the 5 forms of Energy.I like to share this Heat Transfer Rate with you all through my article.

Introduction to the 5 forms of Energy
Energy is defined as the amount of work done by a force.
Energy can neither be created nor be destroyed. It can only be changed from one form to another.
Five forms of energy:
(a) Heat energy

(b) Internal energy

(c) Electrical energy

(d) Chemical energy

(e) Nuclear energy

Description of 5 forms of energy

1. Heat energy :It is the energy possessed by a body by virtue of random motion of the molecules of the body.

2. Internal energy : It is the total energy possessed by the body by virtue of particular configuration on its molecules and also their random motion.  Does internal energy of the body is the some of potential and kinetic energies of the molecules of the body.  Potential energy is due to configuration of the molecules against inter molecular forces and kinetic energy is due to random motion of the molecules.

3. Electrical energy : Electrical energy arises on account of work required to be done in moving the free charge carriers in a particular direction through a conductor.

5 forms of Energy (cont.)

4. Chemical energy : Chemical energy of a body, say a chemical compound is the energy possessed by it by virtue of chemical bonding of its atoms.  The chemical energy becomes available in a chemical reaction.  Chemical energy arises from the fact that the molecules participating in the chemical reaction have different binding energies.  A stable chemical compound has less energy then the separated parts.  A chemical reaction is basically a rearrangement of atoms.

5. Nuclear energy : Nuclear energy is the ;energy obtainable  from an atomic nuclear.  Two distinct modes of obtaining nuclear energy are :

(a)             Nuclear fission

(b)             Nuclear fusion

Nuclear fission involves splitting of a heavy nucleus into two or more lighter nuclei, where as nuclear fusion involves fusing of two or more lighter nuclei to form a heavy nucleus.

Importance of Atmosphere

Introduction to importance of atmosphere:

The envelope of the air which surrounds our earth is called “atmosphere”. In fact, we the human beings and other living organisms live at the bottom of an ocean of air. The atmosphere extends to a height of 120 Km. It is present everywhere on the earth. All living beings need air in one form or another form. Atmosphere is divided into four major layers: Troposphere, Stratosphere, Mesosphere and Thermosphere. The composition of the components of air keeps on changing on the account of following reasons:

Atmosphere is a mixture of gases of different densities among which water vapour is one of the lightest gases, followed by nitrogen, oxygen and carbon dioxide.
There is a drop in temperature and pressure with the increase of height.

Importance of Atmosphere:

Atmosphere plays an important role in the formation of clouds, occurrence of rain and formation of snow. It prevents certain harmful radiations from reaching the surface of the earth. It also helps in the formation of winds. The studies on atmosphere also help in making weather forecasts. The weather forecasts help us in taking necessary measures to prevent loss of human life, cattle and crops due to torrential rainfall, cloud brusts, cyclones and dry spells. It also facilitate in taking appropriate measures against droughts and floods. In a way, weather forecasts help us in disaster management.

Importance of Atmosphere:

The envelope of air protects all living beings from the harmful ultraviolet radiations coming from the sun. These rays can cause skin cancer and various health problems, If they reaches our earth. It plays an important role in the formation of winds. Fast moving winds are used for running windmills. The windmills are used for drawing underground water, flour mills and for generating electricity. Winds do help in the movement of sailing ships, gliders etc. Due to presence of atmosphere, transmission of sound is possible. Some musical instruments work only due to presence of atmosphere. The presence of atmosphere enables earth to maintain suitable temperature on the earth for the survival of the living beings.

Ordinary Dry Cell

Introduction to ordinary dry cell:

The best known voltaic cell for commercial use is the ordinary dry cell. The dry cell which we use in torches, transistor radios, toys and laboratory experiments, was invented by Lechlanche in 1868. The dry cell converts chemical energy into electric energy. A single dry cell gives a voltage of 1.5 volts.

Construction of ordinary dry cell

A dry cell consists of a carbon rod placed at the centre of a zinc container. The space between the carbon rod and the zinc container is filled with a moist paste of ammonium chloride (NH4Cl) and zinc chloride (ZnCl2) mixed with manganese dioxide and powdered carbon. In dry cell, the carbon rod acts as a positive electrode (cathode); the zinc container act as a negative electrode (anode); and the ammonium chloride and zinc chloride acts as electrolyte. Manganese dioxide removes the hydrogen gas formed during the working of dry cell (by oxidising it), and prevent it settling on the positive electrode of the cell (so that it may not interfere with the working of the cell).

How ordinary dry cell works:

Actually, manganese dioxide works as depolariser (depolariser is a chemical which removes hydrogen and prevent it settling on the positive elctrode of the cell). powdered Carbon present in the dry cell helps in the movement of charges between the electrodes in the cell and hence reduces the internal resistance of the cell. Please note that a dry cell is not completely dry. The presence of little water in the miost paste is essential for the movement of ions.The dry cell is sealed at the top with the sealing wax to prevent evaporation of moisture and the carbon rod has a brass cap for better electrical contact. The zinc container has an outer insulation of card board case. The card board case, however does not cover the bottom of the cell. In dry cell , the zinc container is the producer of electrons for the usable current.

Geothermal Resources

Introduction to geothermal resources:

Geothermal energy is the heat from inside the earth, a kind of domestic energy which is reliable, cost effective and environmentally friendlier than other conventional sources of energy. It is released at an average heat flux of 60 mW/m2 by conduction. It is used for direct-heat use and electrical power generation.

Through production wells hot water is pumped up from the underground reservoir for generation of electricity, and then converted to steam by discharge of pressure. The steam is led into a turbine engine, which turns a generator. Remaining geothermal fluid is goes back into the reservoir to maintain its pressure.

Resources for geothermal energy

The global tectonic plates dictate the location of geothermal resources. Geo-dynamic processes like subsidence, sub-duction, uplift, fracturing result in geothermal features like volcanism and hydrothermal convection.

Common geothermal resources are:

A deep simple hot rock or magma body.

Heat carrying fluid.

Fractured or spongy rock.

Top rocks provide an insulating cover

The general geothermal resources need a fluid for heat transfer.

For direct-heat application, heat is extracted from the geothermal water at temperatures less than 120 o C which is used for greenhouse, home heating, vegetable drying and other small scale industries. The hot water spent, is used for direct application.

Technology and Resource Type

Geothermal resources  can be just liquid water, dry, a mixture of steam and water or mainly steam and varies in temperature from 30-350 o C. Water is the medium to transfer geothermal heat from the earth which is naturally occurring in most places but modern technologies extract this energy from hot dry rock resources. The temperature of the resource indicates the type of technologies required or its uses.

Conclusion to geothermal resources

Geothermal electric plants are built on the edges of tectonic plates as high temperature geothermal resources are available close to the surface

There are approximately 8,000 MW of generating and 12,000 MW of direct use geothermal resources world-wide.

Sunday, May 26

Iintroduction to Nuclear Physics

Introduction to nuclear physics:

Matter, right from a tiny speck of dust to a gigantic cosmic entity consists  of atoms. An atom consists of a central part called nucleus around which electrons will revolve. Another question comes to our mind is that whether a nucleus too have a structure like an atom? If so, what is the nature of its constituents and how are they held together in the nucleus? In unfolding such series of questions, a separate branch in physics called  Nuclear physics has evolved.Having problem with Linear Speed Formula keep reading my upcoming posts, i will try to help you.

Introduction to Nuclear Physics by Henri Becquerel

The year 1896, marks the beginning of nuclear physics. It is in this year, the French physicist Henri Becquerel discovered the phenomenon of radioactivity in one of he Uranium compounds, quite accidentally. The phenomenon of radioactivity refers to a particular type of invisible radiation emerging from certain specific substances. At first sight, this radiation was quite puzzling for scientists. Later on the experiments conducted by Ernst Rutherford and others proved that this radiation consists of alpha, beta and gamma rays. This rays were found to be originating in the  nucleus. The experiments conducted by Geiger and Ernst  Marsden, at the suggestion of Rutherford in 1911, involving the scattering of alpha particles have revealed that there exists a positively charged nucleus at the centre of each atom. It was James Chadwick's discovery of neutron in 1932 that clinched the issue of nuclear structure.

Conclusion on Introduction to Nuclear Physics

After the discovery of neutron Werner Heisenberg proposed that the nucleus consists of neutrons and protons. The discovery of artificial radioactivity in 1933 and nuclear fission in 1938, development of first controlled fission reactor in 1942 are some of the important milestones in the field of nuclear physics.

More recently, the scientists are focusing on the nature of nuclear forces and are trying to integrate electro weak force ( which resulted after integrating electromagnetic force and weak nuclear force) ,  strong nuclear force and gravitational force.

Subtracting Vectors Physics

Introduction to Subtracting Vectors Physics

Man's curiosity to know 'nature ' always drives him to evolve new concepts, and identify new relationships among physical quantities. The relationship among the quantities may be of algebraic or geometric in nature. It is cumbersome to represent the relationships geometrically in three dimensions. The concept of vectors and scalars solves this issue. Equations in vector form indicate both mathematical and geometrical relationships among the quantities. Physical laws in vector form and very compact, and independent of choice of coordinate system.I like to share this Displacement Vector with you all through my article.

Subtracting Vectors in Physics : Definition of Vectors

A vector is characterised by an absolute value(magnitude) and a direction. The vector, as a mathematical object, is defined as a directed line segment. Displacement, velocity acceleration, force momentum, angular momentum are a few examples of vector quantities.

A vector is geometrically represented by an arrow. Length of the arrow is proportional to the magnitude of the vector; head of the arrow gives the sense of direction. A displacement vector is represented as an arrow. The initial point( or tail ) of the vector is A, the final point (or head) is B. The length AB ( measured to a scale ) is the magnitude of the vector. The direction of the vector is specified by the angle (in counter clock - wise direction) the arrow makes with a reference line. The magnitude of the displacement is 30m. Its direction is 300 north of east.  In print a vector is represented by a single bold type letter such as d .

Subtraction of Vectors in Physics

Before the operation of subtraction is taken up it is convenient of define negative of a vector.  Negative of a vector is another vector having same magnitude but opposite direction. When a vector and its negative vector are added the resultant is Zero .

i.e.,  a + (-a) = 0. It is said that -a is anti parallel to a.

The concept of negative vector enables one to carry out subtraction of vectors. If vector b is subtracted from vectors a then add -b ( negative of vector b) to a.

a + (-b)  =  a - b