Question

Assertion: Ropes are always made of a number of thin wires braided together. Reason: It helps to ease in manufacturing, flexibility and strength.

A bridge must be designed such that it can withstand the load of the flowing traffic, the force of winds and its own weight. Similarly, in the design of buildings the use of beams and columns is very common. In both the cases, the overcoming of the problem of bending of beam under a load is of prime importance. The beam should not bend too much or break. A bar of length l, breadth b, and depth d when loaded at the centre by a load W sags by an amount given by δ = Wl3/(4bd3Y)