Which is more elastic?

Appeared in: KPSC Staff Nurse - 2015

Explanation

In physics, elasticity is a measure of a material's resistance to deformation, not its ability to stretch.
This property is quantified by Young's Modulus; a higher value indicates greater elasticity.
Steel has a very high Young's Modulus (approximately 200 GPa), significantly higher than glass, concrete, or rubber.
Because steel strongly resists changes in its shape and returns to its original form after stress is removed, it is considered the most elastic among the choices.

Option A: Glass has a lower Young's Modulus (50-90 GPa) than steel. It is also a brittle material, meaning it will fracture under stress rather than deforming elastically and returning to its shape.
Option B: Concrete has a relatively low Young's Modulus (around 30 GPa) and is designed to withstand compression, not tension. It is not a highly elastic material.
Option D: Rubber has a very low Young's Modulus (0.01-0.1 GPa). While it is very 'stretchy' (extensible), this indicates low resistance to deformation, making it one of the least elastic materials in the scientific sense.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Scientific definition of elasticity and Young's Modulus as background academic context rather than a clinical decision trigger.
Understanding material properties like elasticity is crucial in designing medical devices. Surgical instruments are made of steel for its strength and rigidity (high elasticity), while catheters use flexible polymers.
Orthopedic implants (e.g., for hip or knee replacements) must be made from materials with specific elasticity to match bone properties, handle mechanical stress, and ensure longevity.
What if? - If a bone plate used to fix a fracture was made of a material with low elasticity (like a soft polymer), it would not provide the rigid support needed for the bone to heal correctly, leading to instability and malunion.

How to Approach the Question

Identify the core concept being tested: The question asks to compare the 'elasticity' of different materials.
Recall the scientific definition of elasticity. This is different from the everyday meaning of 'stretchy'. In physics, elasticity is the resistance to being deformed.
Relate elasticity to Young's Modulus: A material with a higher Young's Modulus is more elastic.
Compare the materials based on their stiffness. Steel is very stiff and hard to stretch, indicating a high Young's Modulus. Rubber is very easy to stretch, indicating a low Young's Modulus.
Select the material that is the stiffest and most resistant to deformation, which is steel.

Concept Tested & Keywords

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Practise the full KPSC Staff Nurse - 2015

Attempt every question from this paper in a timed mock, then review the full solution for each one.