An aluminium alloy bar with a Young's modulus of 70GPa is under a tensile stress of 10MPa, Which of thefollowing is the equal to the strain in the bar?

A 0.0014
B 7.0x10 3
c 700
D 1.4x10 -4

To find the strain in the bar, we can use the formula:

Strain = (Stress) / (Young's modulus)

Given:
Young's modulus (E) = 70 GPa = 70 x 10^9 Pa
Stress (σ) = 10 MPa = 10 x 10^6 Pa

Substituting the values into the formula:

Strain = (10 x 10^6 Pa) / (70 x 10^9 Pa)

To simplify the calculation, let's convert 70 GPa into Pa:
70 GPa = 70 x 10^9 Pa

Now, substituting the new value:

Strain = (10 x 10^6 Pa) / (70 x 10^9 Pa)
= (10 / 70) x 10^-3
≈ 0.143 x 10^-3

Therefore, the strain in the bar is approximately 1.4 x 10^-4.

So, the correct answer is option D: 1.4 x 10^-4.