Question

Which of the following gives the percent change to the Young's modulus for a substance, when its cross-sectional area is increased by a factor of 3?

• A. 0%
• B. 33%
• C. 300%
• D. 900%

Hint:

Young's modulus is independent of the area and depends only on the material properties.

Answer 1

The Correct Option is A

Young's modulus $Y$ is given by: \[ Y = \frac{\text{Stress}}{\text{Strain}} = \frac{F/A}{\Delta L/L} \] where: $A$ is the cross-sectional area, and $F$ is the force. Since the stress is the force divided by area, an increase in area does not affect the Young's modulus, meaning there is no change to the Young's modulus. Hence, the change is $0%$.