A hydrometre with a uniform cross-sectional area floats in a liquid of density 0.80cm^-3.If the hydrometre wieighs 100.0g and has 12.0cm of its length below the liquid surface , calculate the cross-sectional area of the hydrometre

Explanation:

Let the cross sectional area be a cm .

volume of hydrometer inside liquid = 12 x a = 12 a

weight of liquid displaced = 12a x .8 x g = 9.6 a g

For free floatation of liquid

weight of hydrometer = weight of displaced liquid

9.6 a g = 100 g

a = 10.41 cm²

cross sectional area = 10.41 cm².

fgravity=10x10=100n case 1

fgravity=30x20=600n case 2

6 times more

305.7

explanation:

density =m/v

density =917/3.00

density = 305.

approximately = 305.7

in four significant figures