Poisson's ratio of rubber lies between:
Try it first: pick an option, then read the explanation.
Correct answer: C. 0.45 and 0.50
Asked in SSC JE 23/09/2019 (Morning)
Detailed Explanation
When a material keeps its volume almost constant while deforming, its Poisson's ratio approaches 0.5.
Why “0.45 and 0.50” Is Correct
Rubber changes shape easily but hardly changes volume, so its Poisson's ratio is close to the upper limit: about 0.45 to 0.50.
| Material | Poisson's ratio μ |
|---|---|
| Cork | ≈ 0 |
| Concrete | 0.15 – 0.20 |
| Cast iron | 0.21 – 0.26 |
| Steel | 0.27 – 0.30 |
| Copper | ≈ 0.33 |
| Rubber | 0.45 – 0.50 |
For isotropic materials μ cannot exceed 0.5; above that the volume would decrease under tension.
Why the Other Options Are Wrong
- A. 0.25 and 0.33: 0.25–0.33 is typical of metals.
- B. 0.08 and 0.18: 0.08–0.18 is closer to glass or concrete.
- D. 0.23 and 0.27: 0.23–0.27 is typical of cast iron.
Key Point
μ → 0.5 means incompressible (rubber).
Key Concepts for Students
- μ = 0.5 gives volumetric strain zero under uniaxial stress.
- Elastomeric bridge bearings use rubber.
- Cork (μ ≈ 0) is at the other extreme.
Practice more: this is question 15 in Stress and Strain MCQs – Part 1. Try the whole set and check every answer instantly.