Question

A 30 N object I a hung from a scale and dunked in water (density of 1000 kg/m^3), the measurement on the scale is only 20 N. what is the density of the object? Answer is 3000 kg/m^3, can someone show me how? Would be very appreciated.

Answer 1

object mass = 30/g

weight of water displaced = (30-20)
= 10 N water weight = water mass * g
so water mass = 10 N/g
but water volume = water mass * 1 m^3/1000 kg
so
water volume = (10/g)/1000 meters^3
water volume = .01/g = object volume
so
object mass/object volume
= object mass/ water volume
= 30/g / .01/g = 30*100 = 3000 kg/m^3