Assume the density of brass weights to be 8 g cm-3 and that of air to be 0.0012 g cm-3. What fractional error arises from neglecting buoyancy of air in weighing and object of density 3.4 g cm-l on a beam balance?

Let m gwt the weight of object in vaccum.Volume of object = m3.4Weight of air displaced by object = m3.4×0.0012Volume of brass weight = m8Weight of air displaced by brass weighs = m8×0.0012Error = difference in buoyance      = m0.0012[13.4-18]Fractional error = 0.0012×4.63.4 ×8 = 2 × 10-4