PCM world

Concept This is our common experience that when we go to market to buy something, a few things we always get in definite numbers. For example, eggs we get in a number of 12 which is called a dozen , playing cards we get in a number of 52 which is called a pack, papers we get in a number of 480 sheets which is called a ream. Dozen, pack and ream are units to describe those items. Following chart shows certain items which we get in definite numbers and the units in which these items are described. In Latin, mole means ‘massive heap’ of material. In chemistry, it is a unit which is used to describe an amount of atoms, ions and molecules. It enables chemists to count these particles by weighing. According to 14th conference of National Institutes of Standards and Technology ( NIST ) held in 1971, the definition of mole is given as follows. When the mole is used, the elementary entities must be specified and they may be atoms, molecules, ions, electrons, other parti

Born:  March 14, 1879, Ulm, Germany Died:  April 18, 1955, Princeton, New Jersey, United States Influenced by:  Isaac Newton, Mahatma Gandhi, more Children:  Eduard Einstein, Lieserl Einstein, Hans Albert Einstein Influenced:  Ernst G. Straus, Nathan Rosen, Leo Szilard EINSEIN’S EARLY LIFE (1879-1904) Born on March 14, 1879, in the southern German city of Ulm, Albert Einstein grew up in a middle-class Jewish family in Munich. As a child, Einstein became fascinated by music (he played the violin), mathematics and science. He dropped out of school in 1894 and moved to Switzerland, where he resumed his schooling and later gained admission to the Swiss Federal Polytechnic Institute in Zurich. In 1896, he renounced his German citizenship, and remained officially stateless before becoming a Swiss citizen in 1901. EINSTEIN’S MIRACLE YEAR (1905) While working at the patent office, Einstein did some of the most creative work of his life, prod

There are a number of ways to express the relative amounts of solute and solvent in a solution. This page describes calculations for four different units used to express concentration: Percent Composition (by mass) Molarity Molality Mole Fraction Percent Composition (by mass) We can consider percent by mass (or weight percent, as it is sometimes called) in two ways: The parts of solute per 100 parts of solution. The fraction of a solute in a solution multiplied by 100. We need two pieces of information to calculate the percent by mass of a solute in a solution: The mass of the solute in the solution. The mass of the solution. Use the following equation to calculate percent by mass: Top Molality Molality, m, tells us the number of moles of solute dissolved in exactly one kilogram of solvent. (Note that mola l ity is spelled with two "l"'s and represented by a lower case m.) We need two pieces of information to calculate the molality of a so

A projectile is any object that is cast, fired, flung, heaved, hurled, pitched, tossed, or thrown. (This is an informal definition.) The path of a projectile is called its trajectory. Some examples of projectiles include… a baseball that has been pitched, batted, or thrown a bullet the instant it exits the barrel of a gun or rifle a bus driven off an uncompleted bridge a moving airplane in the air with its engines and wings disabled a runner in mid stride (since they momentarily lose contact with the ground) the space shuttle or any other spacecraft after main engine cut off (MECO) The force of primary importance acting on a projectile is gravity. This is not to say that other forces do not exist, just that their effect is minimal in comparison. A tossed helium-filled balloon is not normally considered a projectile as the drag and buoyant forces on it are as significant as the weight. Helium-filled balloons can't be thrown long distances and don't normally f

Moment of Inertia (Mass Moment of Inertia) -  I  -  is a measure of an object's resistance to changes in the rotation direction. Moment of Inertia has the same relationship to angular acceleration as mass has to linear acceleration. Moment of Inertia of a body depends on the  distribution of mass  in the body with respect to the  axis of rotation For a  point mass  the Moment of Inertia is the mass times the square of perpendicular distance to the rotation reference axis and can be expressed as I = m r 2          (1) where I   = moment of inertia ( kg m 2 ,  slug  ft 2 ) m   = mass (kg,  slugs ) r   = distance between axis and rotation mass (m, ft) Example - Moment of Inertia of a Single Mass Add caption The Moment of Inertia with respect of rotation around the z-axis of a single mass of  1 kg  distributed as a thin ring as indicated in the figure above, can be calculated as I z  = (1 kg) ((1000 mm)(0.001 m/mm)) 2     =  1  kg m 2 Moment of In

DISCUSSION introduction The gas laws are a set of intuitively obvious statements to most everyone in the Western world today. It's hard to believe that there was ever a time when they weren't understood. And yet someone had to notice these relationships and write them down. For this reason, many students are taught the three most important gas laws by the names of their discoverers. However, since the laws are known by different names in different countries and (more importantly) since I can never remember who gets credit for which law without referring to notes, I will not follow this convention. pressure-volume (constant temperature) What happens to the volume of a gas as the pressure on it changes. Let's try the following experiment using equipment that might be found in your kitchen Marshmallows are a mixture of sugar, air, and gelatin. Sugar makes them sweet, air makes them fluffy, and gelatin makes them elastic. Marshmallows are a frozen foam and are mostly a

Born: January 4, 1643, Woolsthorpe-by-Colsterworth, United Kingdom Died: March 31, 1727, Kensington, London, United Kingdom Influenced: Albert Einstein, Edmond Halley, William Whiston, John Theophilus Desaguliers, Thomas Bayes Influenced by: Johannes Kepler, Nicolaus Copernicus Isaac Netwon is synonymous with apples and gravity. He rose to become the most influential scientist of the 17th century, his ideas becoming the foundation of modern physics, after very humble beginnings. But first, the big question: Did an apple really fall on Newton's head and spur him to figure out gravity? Historians say there is likely no more than a grain of truth to the story. Sir Isaac Newton was born, premature and tiny, in 1642 in Woolsthorpe, England. His father, wealthy but uneducated, died before Newton was born, and he ended up being raised by his grandmother after his mother remarried. It’s said he didn’t excel at school, but he ended up studying law at Trinity College Cambri

In radioactive processes, particles or electromagnetic radiation are emitted from the nucleus. The most common forms of radiation emitted have been traditionally classified as alpha ( a ), beta ( b ), and gamma ( g ) radiation. Nuclear radiation occurs in other forms, including the emission of protons or neutrons or spontaneous fission of a massive nucleus. Of the nuclei found on Earth, the vast majority are stable. This is so because almost all short-lived radioactive nuclei have decayed during the history of the Earth. There are approximately 270 stable isotopes and 50 naturally occurring  radioisotopes  (radioactive isotopes). Thousands of other radioisotopes have been made in the laboratory. Radioactive decay will change one nucleus to another if the product nucleus has a greater nuclear binding energy than the initial decaying nucleus. The difference in binding energy (comparing the before and after states) determines which decays are energetically possible and which are n

Any physical quantity requires a numerical value and a standard or scale for its quantitative representation. The standard or the scale by which the physical quantity is represented is known as the UNIT. All physical quantities do not have unit, quantities which are represented as the ration of the two same physical quantities do not have any unit. Example: Refractive Index (μ) =velocity of light in vacuum/velocity of light in medium Specific Gravity = Density of the substance/density of water Generally we have three fundamental physical quantities 1. Mass 2. Length 3. Time They are called fundamental because they do not require the help of other physical quantity for their representation. Most of the other physical quantities can be represented in terms of these physical quantities. When a physical quantity is represented in terms of fundamental quantities it is known as dimension of that physical quantity. Units: Generally we have two types of units 1.

Hope this article will make the learning more fun and interesting. Let’s see what you will study in Std. XI‐XII. Based on the topics you will master mind you can understand how physics is important for you. Physics is the study of nature and natural phenomenon. Scientists discovered the rules that govern the nature. Let’s select few chapters of physics How does a motor cyclist move inside a circular cage in circus?  Have you seen Well of death (mout ka kuan in fun fair), how does they motor cyclist moves in a horizontal circular path and still able to maintain balance. Suppose you are in a bicycle/motor cycle and taking a turn at a very high speed, you need to incline your bicycle to keep balance. How much inclination or bending required depends on your speed.   What holds such huge mass like moon or INSAT series satellites which make them to move around earth? Read carefully centripetal force. During war have you seen anti missile technology, whenever a missile