A rod of length 20 mm is stretched to make a rod of length

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A rod of length 20 mm is stretched to make a rod of length 40 mm. Subsequently, it is compressed to make a rod of final length 10 mm. Consider the longitudinal tensile strain as positive and compressive strain as negative. The total true longitudinal strain in the rod is

1. –0.5
2. –0.69
3. –0.75
4. –1.0

Correct Option: B

Volume remain same L₁ = 20 mm, L₂ = 40 mm, L₃ = 10mm
A₁ L₁ = A₂ L₂ = A₃ L₃

	A₁	=	L₃
	A₃		L₁

True strain = ln		A₁		= ln		L₃		= -0.693
		A₃				L₁