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

Overall changes in volume and radii of a uniform cylindrical steel wire are $0.2 \%$ and $0.002 \%$ respectively when subjected to some suitable force. Longitudinal tensile stress acting on the wire is ($Y = 2.0 × 10^{11} Nm^{-2}$)

When a certain weight is suspended from a long uniform wire, its length increases by one cm. If the same weight is suspended from another wire of the same material and length but having a diameter half of the first one then the increase in length will be ........ $cm$

On all the six surfaces of a unit cube, equal tensile force of $F$ is applied. The increase in length of each side will be ($Y =$ Young's modulus, $\sigma $= Poission's ratio)

A mild steel wire of length $2l$ meter cross-sectional area $A \;m ^2$ is fixed horizontally between two pillars. A small mass $m \;kg$ is suspended from the mid point of the wire. If extension in wire are within elastic limit. Then depression at the mid point of wire will be .............

A stress of $1.5\,kg.wt/mm^2$ is applied to a wire of Young's modulus $5 \times 10^{11}\,N/m^2$ . The percentage increase in its length is