Question

If stress developed in a material is 6 × 10⁷ N/m and strain developed is 2 × 10². What will be the proportionality constant according to Hook's law?
1. 6 × 107 N/m
2. 3 × 105 N/m
3. 12 × 109 N/m
4. None of the above

Answer 1

Correct Answer - Option 2 : 3 × 105 N/m

CONCEPT:

• Hooke's Law: For small deformations, the stress is proportional to the strain produced. 

Stress ∝ strain

stress = k × strain

where k is the proportionality constant.

This k is also known as the modulus of elasticity.

CALCULATION:

Given that stress = 6 × 107 N/m and strain = 2 × 102

We know that 

stress = k × strain

where k is the proportionality constant. So

6 × 107 = k × 2 × 102

k = 3 × 105 N/m

Hence the correct answer is option 2.