The work done in lifting a body of mass 20kg and specific gravity 3.2 to a height of 8m in water is, (g = 10 m/s2)

B = Buoyant force = ρ.vg = ρ . m/σ . gW = mg.: Wa = Apparent weight = mg - mg . ρ/σ.: Work done = Wa.S = mg S (1 - ρ/σ)= 20 x 10 x 8(1-13.2)= 1100 J