Question

Find the greatest length of steel wire that can hang vertically without breaking.Breaking stress of steel `=8.0xx10^(8) N//m^(2)`. Density of steel `=8.0xx10^(3) kg//m^(3)`. Take `g =10 m//s^(2)`.

Answer 1

Correct Answer - A::C::D
Let l be the length of the wire that can having vertically without breaking. Then, the stretching force on its equal to its own weight . If therefore, A is the area of cross-section and p the density, then
Maximum stress `(sigma_m)=weight/A ("stress"="force"/"area")`
Maximum stress `(sigma_m) = "weight"/A`
` sigma_m = (Al_p)g/(A)`
`l=sigma_m/p_g`
Substituting the values `l=(8.0xx10^8)/((8.0xx10^3)(10))=10^4m`