Elasticity
Marcas certain mass and occupies some space. A matter can exist in three state solid, liquid Waste properties and liquid state of matter accounts for surface tension and viscosity while the ange. Each state of matter has some distinct properties. For example, the solid state of matter has keudes. These atoms and molecules hold each other with a force. The force which is responsible to dus state of mutter accounts for pressure, diffusion etc. A matter is made up of atoms and bell the acamus together is called interakonic force and the force responsible to bind the molecules of matter is called intermolecular force. A expression for energy stored in a stretched wire is derived. Finally, related problems both students will get knowledge about young modulus, bulk modulus, shear modulus and Poisson's ratio. Numerical and conceptual are solved in the text as examples and for practice, they are given in the as which enable the students to solve the problems related to this chapter.
🔴 Hooke's Law
Robert Haako studied the elastic behaviour of different objects such as coiled springa, metal rods,
Detallie wires etc. for different deforming forces. He observed, for relatively small deformations of an
pinct, the size of the deformation or displacement is directly proportional to the deforming force. He
seemed up his findings in 1676, which is known as Hooke's law. It is stated as below.
Restoring force acting on a body is directly proportional to extension produced within elastic limit, where k is force constant or spring constant and x is extension produced. Within elastic limit, the object melurns to its original shape and size upon removal of the load. For solids, this law can be explained by the fact that a small displacement of constituent molecules ar atoms from normal positions is also proportional to the force that causes the displacement. The value of force constant k depends on the nature of elastic material and also on its shape and dimensions. It is a number that represents how much force it takes to stretch a material. It is a meture of the spring's stiffness, such that materials with larger spring constants are stiffer.
Hooke's law may also be expressed in terms of stress and strain as in section 8.3
Experimental Verification of Hooke's Law
Suspend a metallic spring AB vertically from a rigid support and attach a scale pan to the lower end
Bof the spring. Fix a pointer P near the end of the spring which can slide over a fixed vertical seale
shown in . When the scale pan is empty, note the reading of the pointer on the scale. Add
Satis known weight on the pan and then, note the reading of painter on the scale again. The difference in
readings will give us the extension in the spring for the weight on the scale pan. Go on adding
etween the weight on the pan and extension in the spring. The graph will be a straight line as depicted
Sameights on the pain in step by step and note the corresponding extensions in the spring
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