Young's modulus requires span distance for extension Steps:

• Calculate weight mg = 0.40 × 9.8 = 3.92 N.
• Angle between sides 60° implies each at 30° to vertical; tension T from 2T cos 30° = 3.92 gives T ≈ 2.26 N.
• Stress = T / A = 2.26 / (2.0 × 10^{-4}) ≈ 1.13 × 10^4 Pa.
• Stretched length per half L from geometry needs pin span D (horizontal projection 2 L sin 30° = D), but D unknown; unstretched halves 0.08 m each, so strain = (L - 0.08)/0.08 undefined without D. Not enough information.

Final answer: Not enough information.