Question

1) A metal weighs 31.16g, then when dipped in water its 29.52g. What is its volume and density of the metal?

2) Britta suggests a possible source of error in this method: At room temperature, the density of water is less than 1g/ml. This means the calculated density is greater than the actual value

Do you agree with Britta's reasoning? Is her reasoning consistent with your results?

Answer 1

1) Weight of object, W= 31.16g,

Apparant weight in water, wa= 29.52g,

Density of water = 1 g/ml

So, density of object/ density of fluid = W/(W-wa)

So, density of object = 31.16/(31.16-29.52)= 19g/ml

So, density of object is 19 g/ml.

2) Density of water at 19°C is = 0.9884 g/ml,

With this density, density of object is = 19×0.9984= 18.9696g/ml.

So, % error in density calculation =

%error= (19-18.9696)×100/18.9696= 0.16%

So % error by density assumption of water as 1g/ml, is only 0.16%.