Due to the addition of impurities,the modulus of elasticity

The two thigh bones (femurs),each of cross-sectional area $10 \; cm^{2}$,support the upper part of a human body of mass $40 \; kg$. Estimate the average pressure sustained by the femurs.

$A$ light rod of length $200\,cm$ is suspended from the ceiling horizontally by means of two vertical wires of equal length tied to its ends. One of the wires is made of steel and has a cross-section of $0.1\,cm^2$,and the other is made of brass with a cross-section of $0.2\,cm^2$. At what distance from the steel wire should a weight be hung along the rod to produce equal stresses in both wires?

The maximum possible height of a mountain on Earth is approximately (elastic limit of mountain rock $= 30 \times 10^7 \ N m^{-2}$,average density of mountain rock $= 3 \times 10^3 \ kg m^{-3}$,$g = 10 \ m s^{-2}$). (in $km$)

In a series combination of copper and steel wires of same length and same diameter,a force is applied at one of their ends while the other end is kept fixed. The combined length is increased by $2 \ cm$. The wires will have ..........

$A$ wire can be broken by applying a load of $200\, N$. The force required to break another wire of the same length and same material,but double in diameter,is .......... $N$.