Question

The stress versus strain graph for wires of two material A & B are as shown in the figure. If Y_A & Y_B are the young's modulus of the materials then 

(A) Y_B = 2Y_A 

(B) Y_A = Y_B 

(C) Y_B = 3Y_A 

(D) Y_A = 3Y_B

Answer 1

Correct option: (D) Y_A = 3Y_B

Explanation:

Y = [(stress) / (strain)] = slope of the graph = tan θ

∴ (Y_A / Y_B) = [(tan θ_A) / (tan θ_B)] = [(tan 60) / (tan 30)] = {√3 / (1 / √3)} = 3

Hence Y_A = 3Y_B