Question

the vol. of the copper piece is thrice that of a iron piece.the copper piece weight 285.5gm more than the iron piece. if the weight of 1 cu m of copper is 8.9gm and that of 1 cu m of iron is 7.8g. find the volume of each piece.

Answer 1

let the vol.of copper be 3V
yhen vol. of irom=V
let the wt. of iron be x
then wt of  copper=285.5+x
given
density of copper=8.9g\cu m
density of iron =7.8g\cu m
now density =mass÷volume

so, 8.9=(285.5+x)÷3V                                   1-eq
now,simlarily
7.8=x÷V
or 7.8V=x 
now put the value of x in eq-1
then you will get V=10.98cu m