Question

The SI unit of stress is same as the SI unit of
A. Strain
B. Modulus of elasticity
C. Pressure
D. Both (2) and (3)

Answer 1

Hint: Here we have to compare as to which of the physical quantities given in the option is similar to that of stress and then we can observe the unit.

Complete step by step answer:
Let us first see what stress and strain is-
Stress is known as the force encountered by the object that causes the object to change, while strain is known as the shift in an object’s form as stress is applied. The unit of stress is $N{m}^{-2}$ .
Stress is a force per unit area that works on a rock. If it is necessary to exceed the intensity of the object that is under stress, stress may trigger pressure. Strain is a shape or size change caused by applied forces. Strain is dimensionless.
Stresses are of two types-
1]Tensile stress
2]Compressive stress
Strains are also of two types-
1]Tensile strain
2]Compressive strain
Modulus of elasticity- the ratio between a stress or force per unit area acting to deform the body and the resulting fractional deformation induced by the stress is represented by each of the elasticity coefficients of a body. The unit for this physical quantity is $N/m^2$ .
Pressure- Pressure is the force applied per unit area over a surface. Its unit is $N/m^2$.
So, from the above discussion we can conclude that both pressure and modulus of elasticity has the same unit as stress.

So, the correct answer is “Option D”.

Note:
Although pressure and stress may appear to be similar but both are different physical quantities. Pressure is the force applied per unit area over a surface whereas stress is the force applied per unit area experienced by something. The young’s modulus is the stress ratio to the strain. Stress has the unit of pressure and strain is dimensionless. So, young modulus also has a unit of pressure.