# help on finding the height of the test tube

• Sep 6th 2009, 12:08 AM
helloying
help on finding the height of the test tube
i know the vol of water is $\displaystyle 8 \frac{1}{3} \pi$

the formula for vol of hemisphere is $\displaystyle \frac{4}{3}$ x $\displaystyle 1.5^2$ x $\displaystyle \frac{1}{2}$ x $\displaystyle \pi$

then i add the formula for vol of cylinder 1/3 x $\displaystyle \pi$x $\displaystyle 1.5^3$x height

i found the height to be $\displaystyle 2 \frac{19}{27}$

now how do i find the height of the hemisphere?
• Sep 6th 2009, 01:48 AM
aidan
Quote:

Originally Posted by helloying
...
the formula for vol of hemisphere is $\displaystyle \frac{4}{3}$ x 1.5^2 x $\displaystyle \frac{1}{2}$ x $\displaystyle \pi$
...

Volume of a sphere
$\displaystyle \dfrac{4}{3} \pi r^3$

The volume of a hemisphere would be half the volume of a sphere.

Quote:

now how do i find the height of the hemisphere?
Double the Diameter of the sphere and Divide by 4

.
• Sep 6th 2009, 03:51 AM
helloying
Quote:

Originally Posted by aidan
Volume of a sphere
$\displaystyle \dfrac{4}{3} \pi r^3$

The volume of a hemisphere would be half the volume of a sphere.

Double the Diameter of the sphere and Divide by 4

.

is this the formula to find height? can u explain to me why?