FLUID MECHANICS -H.C. VERMA- An ornament weighing 36 g in air  weighs 34 g in water. Assuming that some copper is mixed with gold to prepare thr ornament ,find the amount of copper in it . specific gravity of gold is 19.3 and that of copper is 8.9 

                                           .......................2.2 g 

explain!!!!!!!!!!!!!!!!!!!!!!!!!

suppose x grams copper.. then 36-x grams gold.

now the upthrust was 2 grams. (36 -34)

so we say v d g = 2 x 10   (taking g = 10)

or v d = 2

the volume occupied by x grams copper = x / 8.9 and volume occupied by gold = 36-x / 19.3

the net volume of water displaced = x / 8.9 + 36-x / 19.3

d = 1 for water.

so x / 8.9 + 36-x / 19.3 = 2

Perfect solution by shreyasnivas...

In such questions, just use weight of water displaced = upthrust..straight from Archimedes principle..

Take g as 9.8 and you'll get 2.2