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 xx 10^(7) Nm^(-2)) if load of 100000 kg is to be lifted. What should be the radius of steel rope ? What should we do to increase flexibility of such wire ?

The knowledge of elasticity useful in selecting metal ropes show its u

1.	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 xx 10^(7) Nm^(-2)) if load of 100000 kg is to be lifted. What should be the radius of steel rope ? What should we do to increase flexibility of such wire ?
Answer» SOLUTION :The ultimate stress should not EXCEED ELASTIC limit of steel `(30 xx 10^(7) N//m^(2))` `U= (F)/(A)=(Mg)/(PIR^(2))=(10^(5)xx9.8)/(pir^(2))= 30xx10^(7)` `:. R = 3.2` cm So to lift a bad of `10^(4)` kg, crane is designed to withstand 105 kg. To impart flexibility the rope is made of large number of thin WIRES braided.