A steel wire and a copper wire of equal length and equal cross sectionasl area area joined end to end and the combination is subjected to as tension. Find the ratio of as. The stresses developed in the two wire and b. the strains developed. Y of steel `=2xx10^11Nm^-2`. Y o copper `=1.3xx10 11 Nm^-2`.

Answer

A, B, C

Explanation

Given that `L_(steel)=L_(Cu)`
and `A_(steel)=A(Cu)`
`a. (stress of Cu)/(Strees of Steel)=(F_(Cu)A_(Steel))/A_(Cu)F_(Steel))`
`F_(Cu)/F_(Steel)=1`
`[because F_(Cu)=F_(Steel)]`
b. Strain`=(/_\L_(Steel))/(/_\Lcu)`
`=(F_(Steel)L_(Steel)A_(cu)Y_(cu))/(A_(Steel)Y_(Steel)F_(cu)I_(cu))`
`[L_(cu)=L_(Steel):A_(cu)=A_(Steel)]`
`rarr Y_(cu)/Y_(Steel)=(1.3xx10^11)/(2xx10^11)`
`rarr /_\L_(Steel)/(/_\I_(cu)=13/20`
`rarr (/_\_(cu))/(/_\L_(Steel)=20/13`