Question

The knowledge of elasticity useful in selecting metal ropes show its use, in cranes for lifting heavy loads, when rope of steel is used (Elastic limit 30 × 10⁷ Nm^–2) if load of 10⁵ kg is to be lifted. 

What should be the radius of steel rope ? What should we do to increase flexibility of such wire ?

Answer 1

The ultimate stress should not exceed elastic limit of steel (30 × 10⁷ N/m²)

So to lift a bad of 10⁴ kg, crane is designed to withstand 10⁵ kg. To impart flexibility the rope is made of large number of thin wires braided.