Fish Quiz

[Fishmanic]

octopus

 

[sawickib]

nope

 

[Fishmanic]

 barreleye (Macropinna microstoma)

 

[sawickib]

 barreleye (Macropinna microstoma)

your turn!!!

 

[Fishmanic]

to the nearest tenth, how many millilitres of water will an api test tube hold?  and how did you come up with your answer?

 

[TwoTankAmin]

9.0 filled it and poured it into another graduated in 1 ml increments and it looks to be 9.0. It may actually be 8.9 but I need a better beaker to tell for sure.

 

[Fishmanic]

doing it mathematically only knowing that 5ml is at the white line,  what do you come up with-
in other words, do it without actually using a graduated tube

 

[TwoTankAmin]

Well you never said how to figure it out in the first post, so I used the tools on hand. I also have some plastic disposable pipettes for 3 and 1 ml dosing. The 3 ml has .5 ml marks and the 1 ml has .25 ml marks. If I use them I would have to add up several additions- wouldn't said addition be math?

 

[TallTree01]

doing it mathematically only knowing that 5ml is at the white line,  what do you come up with-
in other words, do it without actually using a graduated tube

I'm not going to do it cos I can't be bothered. But mathematically, you'd measure the tube to the white line, and divide that by five. We shall call this X. Now we know how high a tube must be to be exactly one ml.
Then you'd measure the whole tube to the rim. Then you would divide this by X. The answer is how many mls it holds.
You invoked my curiosity, so I used my equation.

I measured to the 5ml line and it was 48 mm or 4.8 centimeters
Divide 4.8 by 5 and we get 0.96 cm or 9.6mm.
Hence 1 ml of water can be held in 0.96 cm of API tube.

The overall height is 8.4cm or 84 mm
Now we divide 84mm by 9.6mm and it is 8.75.
We can assume that the tube can hold around 8.75 ml.
This is an approximate as we must remember that the height includes the base.

*EDIT* made a horrible conversion error.

 

[Mamashack]

8.4ml - used a 5ml syringe filling it twice then deducting what was left in the 2nd syringeful from 10ml after filling the test-tube

mathematically TT would probably be correct however it would wrong as the tube to the line holds approximately 4.7ml rather than the 5 ml it's supposed to so is this an accurate way of calculating?

 

[TallTree01]

8.4ml - used a 5ml syringe filling it twice then deducting what was left in the 2nd syringeful from 10ml after filling the test-tube
mathematically TT would probably be correct however it would wrong as the tube to the line holds approximately 4.7ml rather than the 5 ml it's supposed to so is this an accurate way of calculating?

Hmm, was unaware of this and did not factor it into my calculations.
Why isn't it the 5ml as it says?


3 have answered. 3 different answers. I do not know how to solve this problem when even 2 different results using special equipment differ.
We must allow for small differences in equipment. It is unlikely that 1 ml measured in your syringe is exactly1ml just as my ruler is probably not exactly 30cm long.

 

[Mamashack]

I read in one thread from a few years ago that API said that they allow a margin of error in the volume of water so if it's a bit over or a bit under the line the results are acceptable. Will see if I can find it again, but don't hold your breath!

 

[Mamashack]

Found it!!! Look at #4 for the info
http/www.fishforums.net/index.php?/topic/354671-accuracy-of-api-test-tubes/

 

[daizeUK]

I had also noticed that the API line isn't in the right place.  I always assumed it was just another sign that API kits aren't that accurate
 
Personally if I was doing this question mathematically I'd get a ruler and measure the length of the test tube and its diameter, from that I can work out the volume of a cylinder = pi * radius squared * height
 
Oh drat now I'm going to have to actually do this, it's too early in the morning for this maths malarkey!
 
I measure the height at 8.4cm and inside diameter is 1.1cm so the radius is 0.55cm.
 
Which means the volume is 7.98 cm cubed
 
1ml water takes up 1 cubic cm of space so that's that's my answer - 7.98ml.
 
It sounds like TTA has already empirically disproven this though
 
Another way of doing it would be to fill up the test tube then weight the amount of water it holds, since 1ml roughly weighs 1g (depending on temperature and purity of the water).

 

[Mamashack]

I tried it by weight as daize suggested - on my kitchen scales it was 9g so 9 ml
On my jeweller's scale (got to be accurate when selling aromatherapy products! lol) it weighed 9.1 g so 9.1 ml
Are we any nearer to finding out the answer??
Put us out of our misery please! lol