A constant immersion hydrometer floats vertically in water when the weight of its float is 30 g. When it is made to float in a liquid (miscible in water), the weight of its float is increased by 10 g. Find the weight of the hydrometer when it is floated in a mixture containing equal masses of water and the liquid.

A constant immersion hydrometer floats vertically in water when the we

1.	A constant immersion hydrometer floats vertically in water when the weight of its float is 30 g. When it is made to float in a liquid (miscible in water), the weight of its float is increased by 10 g. Find the weight of the hydrometer when it is floated in a mixture containing equal masses of water and the liquid.
Answer» Solution :(i) In constant immersion Hydrometer, will the level of the immersion of the hydrometer ramain same (constant) ? FIND the weight of the DISPLACED WATER using law of floatation. Is the volume of the displaced water = Volume of the immersed part of hydrometer `=30 cm^(3)` ? What is the weight of the hydrometer when it floats in the liquid ? By using law of floatation, find the density of the liquid. Since, density of the MIXTURE contains equal masses of liquid and water, so, `rho_("mixture")=(M_(W)+M_(L))/(V_(w)+V_(L))=`? But, `V_(L)=(M_(L))/(D_(L)) " and " V_(w)=(M_(w))/(D_(w))` By applying, find the value of `rho_("mixture")`. Substitute the values in, `W=U=Vrho_("mixture"g)` This gives the weight of the hydrometer. (ii)34.28 g