Question

A steel rope attached to a crane is designed to lift up a maximum load of 100 metric ton. What is minimum radius of rope? Given breaking stress of steel = 3.18 x 10⁸ Pa 

Safety factor = 10, g = 10 ms^-2

Answer 1

Maximum load = 100 meteric ton = 10⁵ kg 

Safety factor of 10 means that even if load is ten times of the maximum premitted load the steel rope should not break. Therefore the maximum stress that the rope should be able to withstand = 10 x 10⁵ x 10 / a NM^-2 

where ‘a’ is area of cross-section of rope. This maximum stress is equal to the breaking stress;