Constructing a Hydrometer: Length, Density, & Markings

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Homework Statement

no variable. it give the information about hydrometer>> A hydrometer is to be constructed with a cylindrical floating rod. Nine fiduciary marks are to be placed along the rod to indicate densities of 0.98 g/cm3, 1.00 g/cm3 ,1.02 g/cm3, 1.04 g/cm3, . . . 1.14 g/cm3 . the row of marks is to start 0.200 cm from the top end of the rod and end 1.80 cm. from the top end

Homework Equations

no equation.it ask about
1. What is the required length of the rod?
2. What must be its average density ?
3. Should the marks be equally spaced ?

The Attempt at a Solution

for 1. question >> the length of the rod required to the liquid in that hedrometer or required to what it use for(what it need to measure)
for 2. question >> its everage density up to what inside that hydrometer or all of them have the same density.
for 3. question >> I don't know.

 

[Andrew Mason]

Homework Statement

no variable. it give the information about hydrometer>> A hydrometer is to be constructed with a cylindrical floating rod. Nine fiduciary marks are to be placed along the rod to indicate densities of 0.98 g/cm3, 1.00 g/cm3 ,1.02 g/cm3, 1.04 g/cm3, . . . 1.14 g/cm3 . the row of marks is to start 0.200 cm from the top end of the rod and end 1.80 cm. from the top end

Homework Equations

no equation.it ask about
1. What is the required length of the rod?
2. What must be its average density ?
3. Should the marks be equally spaced ?

What principles apply here? What is the force on the floating rod? How is that related to the volume of liquid displaced by the rod. How is that related to the distance from the liquid level to the bottom of the rod?

AM