1. Jul 10, 2007

### ^DsOoMmI^

1. The problem statement, all variables and given/known data
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

2. Relevant equations
1. What is the required length of the rod?
2. What must be its average density ?
3. Should the marks be equally spaced ?

3. 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.
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Jul 12, 2007

### Andrew Mason

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