Matter and Materials Physics Assignment Essay Example for Free

Matter and Materials Physics Assignment Essay Matter and Materials Part 1 Here is a list of definitions of important terms, with the sources of information in brackets: Tensile Stress (1) Tensile stress is the tensional force acting on a solid per unit cross-sectional area. It is represented by the symbol ? and is measured in N m-2 or Pa. (They are the same thing). Formula: ? = F / A Strain (1) The tensile strain is calculated by dividing the extension produced in a solid (i.e. a wire) under tension, by its original length. It is represented by the symbol ? and has no units. (It is a length divided by a length). Formula: ? = e / l The Young Modulus (1) The Young Modulus is a means by which we can measure a materials relative resistance to tensional force. If a material obeys Hookes Law (as most of them do, at least to an extent) then the tensile stress is proportional to the tensile strain, and the ratio of stress to strain is a constant, which is characteristic of a material. This is called the Young Modulus, and it is calculated by dividing tensile stress by tensile strain. It is represented by the symbol E, and is measured in N m-2 or Pa, as we divide a measurement in Pa by one with no units. Formula: E = ? / ? , or E = F l / A e. Density (1) Density, a characteristic of a material, is defined as mass per unit volume, and is a measure of relative massiveness of a material. Density is represented by the symbol ? and is measured in kg m-3. Formula: ? = m / V Stiff (1) The stiffer a material is, the more difficult it is to be deformed (have its shape or size changed) by a force. Plastic (1) A material is said to be plastic if, when you deform it, it stays in the new shape after the force is released. Elastic (1) If a material is elastic, then it will return to its original shape after being deformed. This is the opposite of plastic. Brittle (1) A brittle material does not change shape at all when a deforming force is applied. It eventually breaks without warning, and the pieces can be fitted back together. Ductile (1) A material is ductile when it can be deformed by a large, steadily applied force. Most economic metals are ductile- they can be drawn out into wire, for example. Tensile Strength (2) The Tensile Strength, or Ultimate Tensile Strength (UTS) of a material, is the amount of tensile stress a material can take just before snapping. It is measured in N m-2 or Pa. Yield Stress (1) The Yield Stress is the amount of tensile stress required for a material to yield. Certain materials, for example mild steel, when under sufficient stress, begin to extend at a very fast rate without additional pressure being applied. This is caused by the materials internal structure losing its integrity. The crystal planes within the metal can slide past each other, and the material becomes completely plastic for a time, but then breaks if any more force is applied. Information Sources 1: A students review notes, found on the college intranet. Address: https://195.195.14.1/intranet/physics/mod_3/12_2_solids/matter/matter.htm 2: Microsoft Encarta 99 Encyclopedia Tensile Strength All of my evidence is in Appendix 1 of the assignment. Information about a metal Aluminium is a very light metal, with a melting point of 660à ¯Ã‚ ¿Ã‚ ½C and a boiling point of 2467à ¯Ã‚ ¿Ã‚ ½C. It is highly electropositive and reactive, and it is this property that makes it extremely resistant to corrosion- on contact with air it rapidly forms a skin of aluminium oxide, which resists any further chemical corrosion. Aluminium is the most abundant metal in the Earths crust, but most of it is contained within complex silicate minerals, from which it is far too expensive to extract. The main source of Aluminium is Bauxite, which is an impure aluminium oxide ore. Part 2 I have been given data for the force and extension from stretching a wire, and the original length and diameter as constants. The formula for the Young Modulus is E = F l / A e , so I will have to manipulate the formula into a graph. If I made a graph of F against e, the gradient would be equal to F / e. Multiplying this by the l / A would give me the Young Modulus. Calculation for the Area A = ? d2 / 4 A = ? (1.0010-3)2 / 4 = 7.8510-7 m2 Therefore l / A = 3.00 / 7.8510-7 = 3.82106 m-1 Below is the spreadsheet data I downloaded. To the right is the graph I constructed from the data.