Atomic view of charges

Atomic view of charges

These properties of Atomic view of charges are readily interpreted in terms of the following model of the atom.



In this model there are some number of protons and neutrons in the nucleus at the center - the protons have positive charge and the neutrons are electrically neutral. Orbiting around the nucleus are electrons, which are negatively charged. Usually atoms have equal numbers of protons and electrons, which means that they are electrically neutral, and therefore normally no electric forces are present. However, when one rubs two objects another, it is possible to transfer some of the outer electrons from one object to another; the protons and neutrons, being about 1800 times more massive than the electrons and bound together in the nucleus, don't move. The object that lost the electrons thus has a deficiency of electrons, leaving it positively charged, and the object that gained the electrons is negatively charged. These two charged objects will thus attract each other because of the electric force between them.

It is also easy to see in this model why charge is quantized in terms of some basic unit - charge arises because of a transfer of electrons, and so all charged objects will have charge equal to an integral number of the basic charge on an electron. This charge, measured in units called Coulombs (C), is given by


which is a very small charge compared to typical charges we usually encounter. What this means is that most charged objects involve the transfer of an enormous number of electrons.

We also can see why in this picture charge is never created nor destroyed (ie, is conserved), as to charge an object means simply to transfer electrons from one object to another. In this process one does not create nor destroy electrons, but just move them.

Laws of Thermodynamics

Laws of Thermodynamics

The field of thermodynamics studies the behavior of energy flow in natural systems. From this study, a number of physical laws have been established. The laws of thermodynamics describe some of the fundamental truths of thermodynamics observed in our Universe. Understanding these laws is important to students of Physical Geography because many of the processes studied involve the flow of energy.

First Law of Thermodynamics

The first law of thermodynamics is often called the Law of Conservation of Energy. This law suggests that energy can be transferred from one system to another in many forms. Also, it can not be created or destroyed. Thus, the total amount of energy available in the Universe is constant. Einstein's famous equation (written below) describes the relationship between energy and matter:
E = mc²

In the equation above, energy (E) is equal to matter (m) times the square of a constant (c). Einstein suggested that energy and matter are interchangeable. His equation also suggests that the quantity of energy and matter in the Universe is fixed.

Second Law of Thermodynamics

Heat cannot be transfer from a colder to a hotter body. As a result of this fact of thermodynamics, natural processes that involve energy transfer must have one direction, and all natural processes are irreversible. This law also predicts that the entropy of an isolated system always increases with time. Entropy is the measure of the disorder or randomness of energy and matter in a system. Because of the second law of thermodynamics both energy and matter in the Universe are becoming less useful as time goes on. Perfect order in the Universe occurred the instant after the Big Bang when energy and matter and all of the forces of the Universe were unified.

Third Law of Thermodynamics

The third law of thermodynamics states that if all the thermal motion of molecules (kinetic energy) could be removed, a state called absolute zero would occur. Absolute zero results in a temperature of 0 Kelvins or -273.15° Celsius.
Absolute Zero = 0 Kelvins = -273.15° Celsius

The Universe will attain absolute zero when all energy and matter is randomly distributed across space. The current temperature of empty space in the Universe is about 2.7 Kelvins.

Hydrostatic Pressure

Hydrostatic pressure

Hydrostatic pressure is what is exerted by a liquid when it is at rest. The height of a liquid column of uniform density is directly proportional to the hydrostatic pressure.

The hydrostatic properties of a liquid are not constant and the main factors influencing it are the density of the liquid and the local gravity. Both of these quantities need to be known in order to determine the hydrostatic pressure of a particular liquid.

The formula for calculating the hydrostatic pressure of a column of liquid in SI units is:

Hydrostatic Pressure (Pa, N/m2) = Height (m) x Density(kg/m3) x Gravity(m/s2)

The density of a liquid will vary with changes in temperature so this is often quoted alongside hydrostatic pressure units e.g. inH2O @ 4 deg C.

The local gravity depends on latitudinal position and height above sea level.

For convenience the most common standard for hydrostatic pressure is metres or inches of water at 4 deg C (39.2 degF) with a standard gravity of 9.80665 m/s2. The density of pure water at 4 deg C is very close to 1000 kg/m3 and therefore this has been adopted as the standard density of water. Another reason for the significance of choosing 4 deg C is that it is very close to the temperature that water reaches its maximum density.

In practical terms hydrostatic pressure units are rarely absolutely precise because the temperature of any liquid is not always going to be 4 deg C. You will also come across another temperature standard of 60 deg F (15.56 deg C). This can lead to confusion and inaccuracies when the temperature is not labelled alongside the hydrostatic pressure unit. For most applications these differences are not significant enough to influence the results since the reading accuracy is often much wider than the difference in the pressure unit conversion factor at these 2 temperatures.

In summary hydrostatic pressure units are a very convenient method for relating pressure to a height of fluid but they are not absolute pressure units and it is not always clear what density/temperature has been assumed in their derivation, so be very cautious when using them for high precision level measurements.

Newton's Laws of Motion

Newton's Laws of Motion

Isaac Newton was born in 1642, the year Galileo died.

Newton's three laws are listed below the way they are usually formulated

"Newton's three Laws of Motion" are the foundation of the theory of motion--e.g., of orbits and rockets.
This section discusses two concepts on which they are based:
Force and Inertia

The 3 Law of Motions are as below

1. In the absence of forces, ("body") at rest will stay at rest, and a body moving at a constant velocity in a straight line continues doing so indefinitely.


2. When a force is applied to an object, it accelerates. The acceleration a is in the direction of the force and proportional to its strength, and is also inversely proportional to the mass being moved. In suitable units:


a = F/m

or in the form usually found in textbooks

F = m a

More accurately, one should write

F = ma

with both F and a vectors in the same direction (denoted here in bold face). However, when only a single direction is understood, the simpler form can also be used.

3. "The law of reaction," sometimes stated as "to every action there exists an equal and opposite reaction." In more explicit terms:


Forces are always produced in pairs, with opposite directions and equal magnitudes. If body #1 acts with a force F on body #2, then body #2 acts on body #1 with a force of equal strength and opposite direction.

Circular motion and rotation

Circular motion and rotation

In pure rotational motion, the constituent particles of a rigid body rotate about a fixed axis in a circular trajectory. The particles, composing the rigid body, are always at a constant perpendicular distance from the axis of rotation as their internal distances within the rigid body is locked. Further the particle from the axis of rotation, greater is the speed of rotation of the particle. Clearly, rotation of a rigid body comprises of circular motion of individual particles.



We shall study these and other details about the rotational motion of rigid bodies at a later stage. For now, we confine ourselves to the aspects of rotational motion, which are connected to the circular motion as executed by a particle. In this background, we can say that uniform circular motion (UCM) represents the basic form of circular motion and circular motion, in turn, constitutes rotational motion of a rigid body.

The description of a circular and hence that of rotational motion is best suited to corresponding angular quantities as against linear quantities that we have so far used to describe translational motion. In this module, we shall introduce these angular quantities and prepare the ground work to enable us apply the concepts of angular quantities to “circular motion” in general and “uniform circulation motion” in particular.

Most important aspect of angular description as against linear description is that there exists one to one correspondence of quantities describing motion : angular displacement (linear displacement), angular velocity (linear velocity) and angular acceleration (linear acceleration).

Measuring Temperature

Measuring Temperature

Temperature is a physical quantity and hence, measurable. In fact in SI system, temperature is a fundamental physical quantity.

Many devices have been invented to accurately measure temperature. It all started with the establishment of a temperature scale. This scale transformed the measurement of temperature into meaningful numbers.

In the early years of the eighteenth century, Gabriel Fahrenheit (1686-1736) created the Fahrenheit scale. He set the freezing point of water at 32 degrees and the boiling point at 212 degrees. These two points formed the anchors for his scale.

Later in that century, around 1743, Anders Celsius (1701-1744) invented the Celsius scale. Using the same anchor points, he determined the freezing temperature for water to be 0 degree and the boiling temperature 100 degrees. The Celsius scale is known as a Universal System Unit. It is used throughout science and in most countries.

There is a limit to how cold something can be. The Kelvin scale is designed to go to zero at this minimum temperature. The relationships between the different temperature scales are:





Measurement of temperature is a very important factor in various scientific experiments. The science of measurement of temperature is known as thermometry. The devices used to measure temperatures are known as thermometers. At a temperature of Absolute Zero there is no motion and no heat. Absolute zero is where all atomic and molecular motion stops and is the lowest temperature possible. Absolute Zero occurs at 0 degrees Kelvin or -273.15 degrees Celsius or at -460 degrees Fahrenheit. All objects emit thermal energy or heat unless they have a temperature of absolute zero.




If we want to understand what temperature means on the molecular level, we should remember that temperature is the average energy of the molecules that composes a substance. The atoms and molecules in a substance do not always travel at the same speed. This means that there is a range of energy (the energy of motion) among the molecules. In a gas, for example, the molecules are traveling in random directions at a variety of speeds - some are fast and some are slow. Sometimes these molecules collide with each other. When this happens the higher speed molecule transfers some of its energy to the slower molecule causing the slower molecule to speed up and the faster molecule to slow down. If more energy is put into the system, the average speed of the molecules will increase and more thermal energy or heat will be produced. So, higher temperatures mean a substance has higher average molecular motion. We do not feel or detect a bunch of different temperatures for each molecule which has a different speed. What we measure as the temperature is always related to the average speed of the molecules in a system

Electrostatics Of Conductors

Electrostatics Of Conductors

• There are two types of charges: positive and negative. Like charges repel and opposite charges attract.

There exist in nature two types of charges: positive and negative. The force between them is such that like charges repel and opposite charges attract. For example, two positive charges brought near each other will be pushed away from each other. On the other hand, one positive charge and one negative charge brought near each other will be pulled towards each other. It is this principle on which all electrostatics is based.

• In general, a material is either a conductor or an insulator. A conductor allows electric charge to travel through it easily; an insulator does not.

Each type of material has a different arrangement of atoms, electrons, and protons. The particular arrangement of a material's atoms can be very advantageous for electric charge to travel through it. Metals, for instance, are very good conductors. Charges can flow through a metal with very little resistance. The particular arrangement of a material's atoms can by disadvantageous, however. Rubber, for instance, has its atoms arranged such that it is very difficult for electric charge to flow through it. Rubber is considered to be an insulator.

• A person's body acts as a conductor.

A person's body allows electric charge to travel through it easily. It is for this reason that one must be careful not to plug in the radio while in the bathtub: electric charges from the outlet can run through your body, electrocuting you.

• When certain types of materials are rubbed against other certain types, charge may be transferred from one to the other.

Each object contains charge. For most objects, the number of negative charges equals the number of positive charges, giving a net charge of zero. These charges are free to move, however. When certain types of materials are rubbed against each other, the material's atoms are arranged such that some of the charges from one material will be transferred to the other material. This gives both objects a net charge. One object will be positively charged, the other will be negatively charged. For example, when a teflon rod is rubbed against silk, charge is transferred.

• When an uncharged object is placed near a charged object its charges rearrange themselves. Those charges attracted to the charged object move towards the charged object and those charges repelled move away. This effect is known as polarization.

As discussed before, most objects are uncharged. An uncharged object means that the total number of positive charges equals the total number of negative charges. The net charge on the object is zero. When an uncharged object is polarized as described above, its net charge remains zero. No additional charge is put on the object. What does happen, however, is the charges inside the object rearrange themselves. When a negatively charged object, for instance, is placed near an uncharged object, the negative charges move away from the charged object and the positive charges move towards the charged object. It is this effect that makes the uncharged object act as if it is charged.

• Charges on a conductor tend to gather at sharp points.

For several complex reasons, the charges on a conductor will gather at sharp points. A metal cone, for instance, which has been charged will have a lot of charge at the point, and much less charge elsewhere.

Why Do We Have to Go to Space to See All of the Electromagnetic Spectrum?

Electromagnetic spectrum

While all electromagnetic waves travel at the same speed (i.e., velocity 'c' is constant), the type of their radiation differs in the duration of wavelength and consequently their frequencies.

An electromagnetic radiation with a long wavelength will have a low frequency and vice versa.

'The arrangement of different types of electromagnetic radiations in order of increasing wavelengths (and consequently decreasing frequencies) is known as electromagnetic spectrum'.

The different types of radiations arranged in an electromagnetic spectrum are: Cosmic rays, gamma rays, X-rays, ultra-violet rays, visible radiations, infrared radiations, micro waves and radio waves.

Electromagnetic radiation from space is unable to reach the surface of the Earth except at a very few wavelengths, such as the visible spectrum, radio frequencies, and some ultraviolet wavelengths. Astronomers can get above enough of the Earth's atmosphere to observe at some infrared wavelengths from mountain tops or by flying their telescopes in an aircraft. Experiments can also be taken up to altitudes as high as 35 km by balloons which can operate for months. Rocket flights can take instruments all the way above the Earth's atmosphere for just a few minutes before they fall back to Earth, but a great many important first results in astronomy and astrophysics came from just those few minutes of observations. For long-term observations, however, it is best to have your detector on an orbiting satellite ... and get below it all!

Electromagnetism

Electromagnetism

An electromagnet can be defined as a soft-iron core that is magnetised temporarily by passing a current through a coil of wire wound on the core.

Michael Faraday

(1791-1867)

Michael Faraday British physicist and chemist, best known for his discoveries of electromagnetic induction and of the laws of electrolysis. His biggest breakthrough in electricity was his invention of the electric motor.

• Michael Faraday the English scientist was the first person to prove that a magnet can create a current
  
  
• To test this he moved a magnet towards and away from the coil of wire connected to a galvanometer
  
  
• He observed that there was a deflection in the galvanometer indicating that a current is induced in it

• The current obtained due to the relative motion between the coil and the magnet is called induced current
  
  
• The phenomenon by which an emf or current is induced in a conductor due to change in the magnetic field near the conductor is known as electromagnetic induction
  
  
• Faraday arrived at a few conclusions by moving a bar magnet in and out of the coil of wire
  
  
• Some of the experiments performed by Faraday and his observations are tabulated here. Go through them

Specular Reflection vs. Diffuse Reflection

Specular vs. Diffuse Reflection

When a ray of light hits a surface, it bounces off or reflects and then reaches our eyes. This phenomenon by which a ray of light changes the direction of propagation when it strikes a boundary between different media through which it cannot pass is described as the reflection of light.

Or in simpler words reflection is the bouncing of light from a smooth surface.

There are two types of reflection of light:

• Regular reflection or specular reflection
• Irregular reflection or diffused reflection

Reflection off of smooth surfaces such as mirrors or a calm body of water leads to a type of reflection known as specular reflection. Reflection off of rough surfaces such as clothing, paper, and the asphalt roadway leads to a type of reflection known as diffuse reflection. Whether the surface is microscopically rough or smooth has a tremendous impact upon the subsequent reflection of a beam of light. The diagram below depicts two beams of light incident upon a rough and a smooth surface.
Why Does a Rough Surface Diffuses A Beam of Light?

For each type of reflection, each individual ray follows the law of reflection. However, the roughness of the material means that each individual ray meets a surface which has a different orientation. The normal line at the point of incidence is different for different rays. Subsequently, when the individual rays reflect off the rough surface according to the law of reflection, they scatter in different directions. The result is that the rays of light are incident upon the surface in a concentrated bundle and are diffused upon reflection. The diagram below depicts this principle. Five incident rays (labeled A, B, C, D, and E) approach a surface. The normal line (approximated) at each point of incidence is shown in black and labeled with an N. In each case, the law of reflection is followed, resulting in five reflected rays (labeled A,, B,, C,, D,, and E,).

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Equilibrium and Statics

Equilibrium and Statics

Static friction is the friction experienced when we try to move a stationary body on a surface, without actually causing any relative motion between the body and the surface which it is on.

When all the forces which act upon an object are balanced, then the object is said to be in a state of equilibrium. The forces are considered to be balanced if the rightward forces are balanced by the leftward forces and the upward forces are balanced by the downward forces. This however does not necessarily mean that all the forces are equal to each other. Consider the two objects pictured in the force diagram shown below. Note that the two objects are at equilibrium because the forces which act upon them are balanced; however, the individual forces are not equal to each other. The 50 N force is not equal to the 30 N force.

If an object is at equilibrium, then the forces are balanced. Balanced is the key word which is used to describe equilibrium situations. Thus, the net force is zero and the acceleration is 0 m/s/s. Objects at equilibrium must have an acceleration of 0 m/s/s. This extends from Newton's first law of motion. But having an acceleration of 0 m/s/s does not mean the object is at rest. An object at equilibrium is either ...

• at rest and staying at rest , or

• in motion and continuing in motion with the same speed and direction.

The Human Ear

The Human Ear

Ears are extremely sensitive device with the help of which we are able to hear.

The ear consists of three basic parts - the outer ear, the middle ear, and the inner ear. Each part of the ear has a specific role in the task of detecting and interpreting sound. The outer ear is called pinna. It collects and transmits the sound to the middle ear through the auditory canal.

Understanding how humans hear is a complex subject involving the fields of physiology, psychology and acoustics. In this part of Lesson 2, we will focus on the acoustics (the branch of physics pertaining to sound) of hearing. We will attempt to understand how the human ear serves as an astounding transducer, converting sound energy to mechanical energy to a nerve impulse which is transmitted to the brain. The ear's ability to do this allows us to perceive the pitch of sounds by detection of the wave's frequencies, the loudness of sound by detection of the wave's amplitude and the timbre of the sound by the detection of the various frequencies which make up a complex sound wave.

At the end of the auditory canal there is a thin membrane called the eardrum or tympanic membrane. The eardrum moves inward and outward as the compression or rarefaction reaches it. In this way the eardrum vibrates. These vibrations are amplified by the three bones namely the hammer, anvil and stirrup in the middle ear.

The middle ear transmits these vibrations to the inner ear. Inside the inner ear, the vibrations or the pressure variations are converted into electrical signals by the cochlea. These electrical signals are sent to the brain via the auditory nerve and the brain interprets them as sound.

Kinetic Energy

Kinetic energy : Kinetic energy is the energy of motion. An object which has motion - whether it be vertical or horizontal motion - has kinetic energy. There are many forms of kinetic energy - vibrational (the energy due to vibrational motion), rotational (the energy due to rotational motion), and translational (the energy due to motion from one location to another). To keep matters simple, we will focus upon translational kinetic energy. The amount of translational kinetic energy (from here on, the phrase kinetic energy will refer to translational kinetic energy) which an object has depends upon two variables: the mass (m) of the object and the speed (v) of the object. The following equation is used to represent the kinetic energy (KE) of an object.



This equation reveals that the kinetic energy of an object is directly proportional to the square of its speed. That means that for a twofold increase in speed, the kinetic energy will increase by a factor of four. For a threefold increase in speed, the kinetic energy will increase by a factor of nine. And for a fourfold increase in speed, the kinetic energy will increase by a factor of sixteen. The kinetic energy is dependent upon the square of the speed. As it is often said, an equation is not merely a recipe for algebraic problem-solving, but also a guide to thinking about the relationship between quantities.

Kinetic energy is a scalar quantity; it does not have a direction. Unlike velocity, acceleration, force, and momentum, the kinetic energy of an object is completely described by magnitude alone. Like work and potential energy, the standard metric unit of measurement for kinetic energy is the Joule. As might be implied by the above equation, 1 Joule is equivalent to 1 kg*(m/s)^2.

Circuit Symbols and Circuit Diagrams

Circuit Symbols and Circuit Diagrams

Electric circuits, whether simple or complex, can be described in a variety of ways. An electric circuit is commonly described with mere words. Saying something like "A light bulb is connected to a D-cell" is a sufficient amount of words to describe a simple circuit.








A final means of describing an electric circuit is by use of conventional circuit symbols to provide a schematic diagram of the circuit and its components. Some circuit symbols used in schematic diagrams are shown below.




A single cell or other power source is represented by a long and a short parallel line. A collection of cells or battery is represented by a collection of long and short parallel lines. In both cases, the long line is representative of the positive terminal of the energy source and the short line represents the negative terminal. A straight line is used to represent a connecting wire between any two components of the circuit. An electrical device which offers resistance to the flow of charge is generically referred to as a resistor and is represented by a zigzag line. An open switch is generally represented by providing a break in a straight line by lifting a portion of the line upward at a diagonal. These circuit symbols will be frequently used throughout the remainder as electric circuits are represented by schematic diagrams. It will be important to either memorize these symbols or to refer to this short listing frequently until you become accustomed to their use.

Example

Description with Words: Three D-cells are placed in a battery pack to power a circuit containing three light bulbs.


Using the verbal description, one can acquire a mental picture of the circuit being described. But this time, the connections of light bulbs is done in a manner such that there is a point on the circuit where the wires branch off from each other. The branching location is referred to as a node. Each light bulb is placed in its own separate branch. These branch wires eventually connect to each other to form a second node. A single wire is used to connect this second node to the negative terminal of the battery.

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Alcoholic beverage

Alcoholic beverage: An alcoholic beverage is a drink containing ethanol (commonly called alcohol). Alcoholic beverages are divided into three general classes: beers, wines, and spirits.

Alcohol content of beverages

The concentration of alcohol in a beverage is usually stated as the percentage of alcohol by volume (ABV) or—in the United States—as proof. In the U.S., proof is twice the percentage of alcohol by volume at 60 degrees Fahrenheit (e.g., 80 proof = 40% ABV). Degrees proof were formerly used in the United Kingdom, where 100 degrees proof was equivalent to 57.1% ABV. Historically, this was the most dilute spirit that would sustain the combustion of gunpowder.

Ordinary distillation cannot produce alcohol of more than 95.6% ABV (191.2 proof) because at that point alcohol is an azeotrope with water. A spirit which contains a very high level of alcohol and does not contain any added flavoring is commonly called a neutral spirit. Generally, any distilled alcoholic beverage of 170 proof or higher is considered to be a neutral spirit.[6]

Most yeasts cannot reproduce when the concentration of alcohol is higher than about 18%, so that is the practical limit for the strength of fermented beverages such as wine, beer, and sake. Strains of yeast have been developed that can reproduce in solutions of up to 25% ABV.

Effect of Alcohol on Human Beings

Effect of Alcohol

Chemically the term alcohol refers to a group of organic compounds, having -OH group in their composition. But the word alcohol used by the common man refers to ethyl alcohol or ethanol. It has a variety of uses, especially as a solvent.n small quantities it may serve as a source of energy, but in large amounts, it affects the nervous system. The person experiences loss of control over muscles and loses his or her sense of balance and mental ability. It can be a habit forming activity. If consumed over a period of time, alcohol can ruin one's health especially the liver, which gets affected by cirrhosis. This type of consumption can be fatal and ruins one's family life.

Hydrocarbons

Definition of Hydrocarbons: The simplest organic compounds are hydrocarbons. All organic compounds can be derived from hydrocarbons by substituting a hydrogen atom with a suitable functional group. Replacing a hydrogen atom by a OH group in a hydrocarbon, gives an alcohol: replacement of H atom in a hydrocarbon by COOH group gives in a hydrocarbon carboxylic acid, and so on. It is therefore appropriate to begin the study of hydrocarbons with its preparation, properties and reactions.

Hydrocarbons can be classified as follows:

Types Of Hydrocarbons

1. Alkanes

2. Alkenes

3. Alkynes

4. Aromatic

Several specific forms of hydrocarbons-

• Dry gas- contains largely methane, specifically contains less than 0.1 gal/1000ft3 of condensible (at surface T and P) material.
• Wet gas- contains ethane propane, butane. Up to the molecular weight where the fluids are always condenced to liquids
• Condesates- Hydrocarbon with a molecular weight such that they are gas inthe subsurface where temperatures are high, but condence to liquid when reach cooler, surface temperatures.
• Liquid hydrocarbons- commonly known as oil, or crude oil, to distinguish it from refined hydrocarbon products.
• Plastic hydrocarbons- asphalt
• Solid hydrocarbons- coal and kerogen- (kerogen strictly defined is dessimenated organic matter in sediments that is insoluble in normal petroleum solvents.
• Gas hydrates- Solids composed of water molecules surrounding gas molecules, usually methane, but also H2S, CO2, and other less common gases.
  

Measurement of Length

Measurement of length: Different types of lengths are measured by using different types of instruments. Lengths like the length of cloth or length of a line can be measured by using measuring tape, a metre scale or a foot rule. But these instruments cannot be used to measure the diameter of a metal sphere or a cylinder. To measure the diameter of a cylinder we can use paper strip method and wooden block method:

(i) Length is a measurement of distance or dimension. The two main systems to measure length are the metric and the English system. The metric system is based on 10 as you can see in the table above. The meter is the standard unit and portions of that are in tens. You can see the difference between a centimeter and a millimeter in the picture below. Always read a ruler in a direct line, not at an angle.

Conversion Chart

1 centimeter = 0.3937 inches
12 inches = 1 foot
1 inch = 2.54 centimeters
1 foot = 0.3048 meters
3 feet = 1 yard
1760 feet = 1 mile
5280 feet = 1 mile
1 yard = 0.9144 meters
1 meter = 3.28083 feet
1 kilometer = 3281 feet
1 kilometer = 0.6214 miles
3 miles = 1 league

Zeroth law of Thermodynamics

Zeroth law of Thermodynamics: The 'zeroth law' states that 'if two bodies (say A and B) are in thermal equilibrium with another body C, then the bodies A and B will also be in thermal equilibrium with each other'. This law is important as it helps in understanding the concept of temperature.

Explanation: For example, If A is in thermal equilibrium with B and C, then B is in thermal equilibrium with C. This means that all three are at the same temperature, and it forms a kind of ground for comparison of temperatures. It is called the Zeroth Law because it precedes the First and Second Laws of Thermodynamics.




Zeroth Law of Thermodynamics and Thermometers

The below is an sample problem is for Zeroth Law of Thermodynamics

Question: In a constant-volume gas thermometer how can you measure temperature by measuring the pressure of the gas?


Answer: When a gas is heated the pressure increases if it is restricted to a fixed volume. When a gas is cooled the pressure decreases at constant volume. This effect is used to measure temperature by measuring the pressure of the gas when it is placed in thermal contact with the substance whose temperature is being measured. If the pressure of a gas in a constant-volume thermometer is plotted versus temperature a straight line is obtained. If you extend the line down to zero pressure you find the temperature at this point to be -273.15 degrees Celsius.

carbon cycle

Carbon Cycle Definition: The carbon cycle describes the storage and exchange of carbon between the Earth's biosphere (living matter), atmosphere (air), hydrosphere (water), and geosphere (earth).

Carbon is an element that is essential for life as we know it. Living organisms obtain carbon from their environment. When they die, carbon is returned to the non-living environment. However, the concentration of carbon in living matter (18%) is about 100 times higher than the concentration of carbon in the earth (0.19%). The uptake of carbon into living organisms and return of carbon to the non-living environment are not in balance.

Forms of Carbon in the Carbon Cycle

Carbon in the Non-Living Environment

The non-living environment includes substances that never were alive as well as carbon-bearing materials that remain after organisms die. Carbon is found in the non-living part of the hydrosphere, atmosphere, and geosphere as:
carbonate (CaCO3) rocks: limestone and coral
dead organic matter, such as humus in soil
fossil fuels from dead organic matter (coal, oil, natural gas)
carbon dioxide (CO2) in the air
carbon dioxide dissolved in water to form HCO3−

How Carbon Enters Living Matter

Carbon enters living matter through autotrophs, which are organisms capable of making their own nutrients from inorganic materials.
Photoautotrophs are responsible for most of the conversion of carbon into organic nutrients. Photoautotrophs, primarily plants and algae, use light from the sun, carbon dioxide, and water to make organic carbon compounds (e.g., glucose).

Chemoautotrophs are bacteria and archaea that convert carbon from carbon dioxide into an organic form, but they get the energy for the reaction through oxidation of molecules rather than from sunlight.

How Carbon Is Returned to the Non-Living Environment

Carbon returns to the atmosphere and hydrosphere through:
burning (as elemental carbon and several carbon compounds)
respiration by plants and animals (as carbon dioxide, CO2)
decay (as carbon dioxide if oxygen is present or as methane, CH4, if oxygen is not present)

Law Of Conservation Energy and Momentum

Conservation Energy: Energy states that the energy can neither be created nor destroyed but can be transformed from one form to another.

Momentum:Momentum of the body is defined as the product of its mass and the velocity.

Law Of Conservation Energy

The Law of Conservation of Energy states that "the total energy of an isolated system is conserved or said to be constant over time". It can also be said that "energy cannot be created or destroyed , but it can be transformed from one form to another form".

Conservation means to result in no net loss of a particular component. So the law says that there is no loss of energy in any isolated system. According to the statement of the law the total energy in the universe if fixed and it cannot be decreased or increased. Thus the energy is converted from one form to another form such as from heat energy to mechanical energy or chemical energy or electrical energy and so on and there is no loss of energy during this process. The energy either remains in one or the other form, but is not lost completely.

Law Of Momentum

Momentum is a vector quantity. It is normally denoted by the letter ‘p’.

So momentum,p= mass(m) x velocity(v) =m _* v. The unit of momentum is Kg m/s in MKS and g cm/s in CGS system.

Law of conservation of momentum states that momentum is a conserved quantity like energy.

Law of conservation of momentum is originally modulated from Newton’s second law of motion. The application level of law of conservation of momentum is seen in electrodynamics, quantum mechanics, quantum field theory and general relativity.