Question

In a cable suspension bridge, the cable is assumed to be:

• A. Perfectly flexible
• B. Perfectly inflexible
• C. Inextensible
• D. Perfectly flexible and extensible

Hint:

Suspension bridge cables are modeled as inextensible to ensure that they only carry tension and maintain their length under load.

Answer 1

The Correct Option is C

Step 1: Understand cable mechanics.
In cable structures like suspension bridges, the cable's shape adapts to applied loads, forming a catenary or parabolic profile. This shape is governed by the assumption that the cable cannot resist compression or bending.
Step 2: Definition of inextensibility.
An inextensible cable means its length does not change under load — it only develops tension. This is critical in ensuring the geometry remains consistent during structural analysis.
Step 3: Why not flexible or extensible?
"Perfectly flexible" only refers to no bending stiffness.
"Extensible" would mean the cable stretches, which isn't true for ideal suspension bridge modeling.
Therefore, the cable is assumed inextensible to simplify analysis and match real-life behavior closely.