Question

Which of the following is incorrect

• A. Stress is not a vector quantity.
• B. Young's modulus is only applicable for solids.
• C. Compressibility is applicable for solids, liquids and gases.
• D. Young's modulus is greater for elastomers than metal.

Hint:

Do not confuse the everyday usage of the word "elastic" with the physics definition of "elasticity."
In physics, highly elastic materials (like steel) resist deformation strongly and swiftly return to shape, whereas elastomers have low elasticity and stretch easily.

Answer 1

The Correct Option is D

To solve the question, let's analyze each option carefully and understand the relevant physics concepts:

1. Stress is not a vector quantity.
   Stress is a measure of internal force per unit area within materials that arises due to externally applied forces. It is a tensor quantity, not a vector, because it describes both the magnitude and direction of internal forces in multiple dimensions. Therefore, this statement is correct.
2. Young's modulus is only applicable for solids.
   Young's modulus is a property that measures the stiffness of a solid material. It describes the relationship between tensile stress (force per unit area) and tensile strain (proportional deformation) in materials. It is indeed predominantly applicable to solids as it characterizes elastic properties under linear elastic deformation. This statement is correct.
3. Compressibility is applicable for solids, liquids, and gases.
   Compressibility is a measure of the relative volume change of a material or fluid in response to a pressure change. It is a property that applies to solids, liquids, and gases. This statement is correct.
4. Young's modulus is greater for elastomers than metal.
   Young's modulus is a measure of a material's ability to resist deformation in response to an applied force. Elastomers, such as rubber, have a much lower Young's modulus compared to metals. This is because elastomers are much more flexible and exhibit greater elastic deformation under stress. Thus, Young's modulus is typically greater for metals than elastomers. Therefore, this statement is incorrect.

By evaluating each option, we find that the incorrect statement is "Young's modulus is greater for elastomers than metal." This aligns with the provided correct answer.