The breaking stress of a wire of length $L$ and radius $r$ is $5 \ kg-wt/m^2$. The wire of length $2L$ and radius $2r$ of the same material will have a breaking stress in $kg-wt/m^2$ of:

The two thigh bones (femurs),each of cross-sectional area $10 \, cm^2$,support the upper part of a person of mass $50 \, kg$. The average pressure sustained by the femurs is ............. $N/m^2$.

The length of an elastic string is $a$ metres when the longitudinal tension is $4 \ N$ and $b$ metres when the longitudinal tension is $5 \ N$. The length of the string in metres when the longitudinal tension is $9 \ N$ is

The dimensions of stress are equal to

Hooke's law defines:

The increase in length is $l$ of a wire of length $L$ by the longitudinal stress. Then the stress is proportional to