Question

a 2.0 kg solid mass has an apparent weight 12.34N when totally immersed in water. Calculate the apparent weight of the body when totally immersed in a liquid of density 0.78

Answer 1

2 kg * 9.81 = 19.62 N weight

loses (19.62-12.34) = 7.28 N in water

7.28 N /9.81 = .7421 Kg of water displace

.7421 kg * 1 m^3/1000 kg = 7.421 * 10^-4 m^3 = volume of mass

mass of light fluid displaced =
7.421 *10^-4 m^3 * .78 * 10^3
= .579 kg
weight of light fluid displaced =
.579*9.81 = 5.68 N of light fluid displaced
so apparent weight = 19.62 - 5.68 = 13.9 Newtons
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OR MORE EASILY IF I had thought a little
2 kg * 9.81 = 19.62 N weight

loses (19.62-12.34) = 7.28 N in water
but in our fluid it will lose .78 * 7.28 = 5.68 N
19.62 - 5.68 = 13.9 N

Answer 2

thanks Damon