Aditya Abeysinghe Presentations

Weightlessness is the absence of stress or strain resulting from external forces, as usually experienced by a person or simply occurs when there is no force of support on your body. Weightlessness is a concept, in which the person who is experiencing it experiences,                         1. . Zero weight                         2.  Free fall Weightlessness can occur due to several reasons:                    1.  In a satellite E.g.: Assume a satellite of mass ‘m’ orbiting around a planet of mass M at a distance R from the center of the planet. The acceleration of the spacecraft and astronaut (mass m 1 ) are both g 0 in magnitude, where g 0 is the acceleration due to gravity at a distance R. If S is the reaction of the surface of the spacecraft in contact with the astronaut, then, for circular motion, F = m 1 g 0 – S = m 1 a =m 1 g 0  Thus, S = 0 Thus, the astronaut now does not experience any reaction from the surface of contac

Introduction: Flame test is an experiment used to identify/distinguish metals using colors exposed to a flame.  Since metallic halides easily evaporate, the test is usually done using the halide components of metals. Out of the halides, chlorides are frequently used because chlorides give a fast change of color when exposed to the flame as opposed to other halides. Materials needed:       ·           A rod of platinum, nichrome, asbestos or graphite      ·          Concentrated HCl solution      ·          Bunsen burner      ·          Metallic salt (a chloride of a metal)      ·          A cobalt glass (if necessary) Method: Insert the rod of platinum, nichrome, asbestos or graphite into a concentrated solution of HCl. Hold the rod to a Bunsen flame. (to the  colorless region) Continue this experiment until the top region of the flame turns colorless. Form a pulp by mixing the metallic salt with the concentrated HCl solution and apply

The expansion of water when cooled from four degrees centigrade to zero degrees centigrade is known as the "anomalous expansion of water." Before examining the anomalous expansion of water let’s examine how other liquids react with changing volume and density above 273K. When the temperature of a system, in which the liquid is stored, increases due to the volumetric expansion of the system, the volume of the liquid also increases. However, by definition, density is the mass per unit volume or according to popular equation d = m /v. Thus, there exists an inverse relationship between the density of a liquid and its volume, when the mass is constant. Meanwhile, when the volume of a liquid increases with increasing temperature, above 273K, the density of the liquid should decrease. But, what differ water from other liquids is the presence of hydrogen bonds in water. Though ice is supposed to expand when it is converted into water, formation of hydrog