IIT JEE , AIEEE Forum - Physics , Mechanics

chimanshu_007

hiiee

Poission's ratio - Wen a wire susepended frm 1 end and loaded at the other , it not only increases its length but also decreases its diameter . In other words , an elongtational starin is accompanied by a lateral starin also in a direction perpedcular to its length. The ratio of lateral strain to the longitudanal strain is called poission's ratio ()

Let L and D be the original length and diameter of the wire resp. . Suppose delta L and delta D be the small increase in length and correspondingly small decrease in diameter of the wire

longitudinal strain = del. L / L

and lateral strain = - (del. D / D)

so

= (-del D/D) / (del. L / L)

P.S- its a pure no. and hence dimension less .

its value lies between -1 and 0.5

but it is never -ive in actual practise and its practical value lies b/w 0 and 0.5

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