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Questions on Stresses

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       Consider two beams A & B. Beam A  and B  are positioned in horizontal direction and vertical direction respectively. Breadth of both beams is 2 cm. Initially the setup was at a stable environment of temperature 38 o C but suddenly the temperature hits 120 o C. Beam A is weightless and beam B has a weight of W. Find the deflection of beam A. E A =2x10 5 N/mm 2 ; E B =9.65x10 6 N/mm 2           Consider the following: Two poles each carrying thick circular cross-sectional wires of diameter 2 cm are separated by a distance of 10 m. The two wires are initially loosened such that they can be imagined to be segments of a circle of radius R. Conditions arises such that the upper wire receives heat and lower wire rejects heat. The initial temperature of both the wire is same and the amount of heat absorbed and rejected by the wires is same. Both wires are carrying current I. Find the maximum temperature suc

Thermal Stress

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When an object is supplied with a finite amount of heat, the atom presents in the lattice structure starts agitating, and they tend to leave their stable position and starts to oscillate about their mean position. Due to the inter-atomic forces of attraction the neighbouring atoms also starts vibrating with the frequency equal (ideal case) or less (non-ideal case) than that of the previous atom. This phenomenon leads the transfer of heat. There are many processes by which an abject can be heated, but the mode of transfer of heat inside a body remains same. Due to this agitation, the body tries to undergo either a linear, surface or volumetric expansion depending upon the dimensions we choose. Under this expansion, whenever the body is subjected to and hindrance, stresses are developed and this stress is called thermal stress . Consider the following situation: Body absorbing heat Suppose a block is placed upon a smooth frictional-less surface and heat is being tr

Stresses

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Stress being generated Stress is the property by which a body tends to resist the changes in its dimension when an external force is applied on a body. It is usually denoted by  σ( sigma).  Reason: Stress traces its origin from the molecular and atomic level , i . e, the microscopic level. When a force is applied under elastic limit, work is done in order to overcome the molecular forces of attraction and this work is stored in the form of elastic potential energy. This give rise to opposing forces which tries to resist the externally applied forces. When the forces are removed the distorted lattice of molecules regains its shape, depending upon the magnitude of external force and the property of material. If the force, however small it may be, exceeds the elastic limit of the body then the original shape of the body is not regained and vice versa. Stresses are forces which are confined inside the geometry of the body and no such devices exist till date wh