STRESS & STRAIN

Hooke’s Law is valid within:

• Elastic limit

• Plastic range

• Yield point

• Breaking point

Which of the following is the correct unit of stress?

• N/m

• N

• N/m²

• m²/N

Answer explanation

Stress = Force / Area. SI unit of force is Newton (N), and area is m². Hence, the unit of stress = N/m², which is also called a Pascal (Pa).

What type of stress is developed when a material is subjected to equal and opposite forces acting away from it?

• Shear Stress

• Compressive Stress

• Bending Stress

• Tensile Stress

Answer explanation

When forces act away from the material and try to elongate it, tensile stress is developed. If forces act towards each other (trying to compress the material), compressive stress is developed.

A bar of 2 m length elongates by 1 mm under an axial load. What is the strain in the bar?

• 0.005

• 0.0005

• 0.05

• 0.00005

Answer explanation

Strain is calculated as the change in length divided by the original length. Here, the change in length is 1 mm and the original length is 2000 mm (since 2 m = 2000 mm). So, strain = 1 mm / 2000 mm = 0.0005 (a unitless quantity).

What is the modulus of elasticity also known as?

• Shear Modulus

• Young's Modulus

• Bulk Modulus

• Poisson’s Ratio

If a material returns to its original shape after removing the load, the behavior is called:

(a)  

Answer explanation

Elastic behavior is characterized by the ability of a material to return to its original shape after the load is removed.

Which of the following materials is most elastic?

• Copper

• Steel

• Rubber

• Brass

If a piece of material neither expands nor contracts in volume when subjected to stresses, then the Poisson’s ratio must be

• Zero

• 0.25

• 0.35

• 0.5

Assertion : Stress and modulus of elasticity have the same dimensions. Reason: The dimensional formula of Strain is [L].

• Both A and R are true and R is the correct explanation of A

• Both A and R are true but R is not the correct explanation of A

• A is true but R is false

• A is false but R is true

Which of the following material has Poisson's ratio greater than

• Steel

• Cork

• Copper

• None