The elasticity of Invar:

$A$ wire of length $l$ and cross-sectional area $A$ is stretched by a weight $Mg$ such that its length becomes double. What is the stress in the wire?

$A$ wire can be broken by applying a load of $20 \, kg$ weight. The force required to break the wire of twice the diameter is .......... $kg \, wt$.

The elastic limit of brass is $3.5 \times 10^{10} \, N/m^2$. Find the maximum load that can be applied to a brass wire of $0.75 \, mm$ diameter without exceeding the elastic limit $....... \times 10^4 \, N$.

For what reasons can the elastic behavior of a solid body be explained?

The ratio of radii of two wires of same material is $2: 1$. If these wires are stretched by equal force,the ratio of stresses produced in them is .............