an iron casting consists of cavities it wieghs 6000N in air and 4000N in water.the density of iron is 7.8g/cm3 find the volume occupied by the cavities

can u pls explain the 2nd eqn??

Its a simple application of Archimedes Principle.....

see....from the given data.....

Volume of the Body =  ( Loss in weight of the body ) / (density of water x g)

                                  =   ( 6000 - 4000 ) / ( 0.001 kg cc^-3 x 9.8 )

                                  =   204081.63 cc³

Now Volume of the material in the body = mass of body / density of material

= 6000 / (0.0078 kg cc^-3 x 9.8)

= 78492.93 cc³

So Volume of the cavities = 204081.63 - 78492.93 = 125588.7 cc³  

I hope there is no Calculation mistake.......

cheers!!!

thanx guys