A body weighs 20N in air and 15N in another liquid. If it's weighs18N in water, calculate the relative density of the liquid

Answer 1

density of water = 1000 kg/m^3
force up from water on body = 20 - 18 = 2 N
so if V = volume of body
V* 1000 kg/m^3 * g= 2 N
V = 2/1000 g
force up from fluid = 20 -15 = 5 N
V * rho * g = 5
rho = 5 (1000 g /2) /g = 2.5 * 1000 = 2.5 times density of water