What is the minimum height of the bag needed for glucose infusion?

[DrMcDreamy]

Homework Statement

A collapsible plastic bag contains a glucose solution. If the average gauge pressure in the vein is 15000 Pa, what must be the minimum height of the bag in order to infuse glucose into the vein? Assume that the specific gravity of the solution is 1.04. The acceleration of gravity is 9.8 m/s². Answer in units of m.

Homework Equations

P=\rhogh

The Attempt at a Solution

I don't know what the units of the specific gravity so I assumed its 1.04 g/c,³. So it becomes 1040 kg/m³.

So would it be:

P=\rhogh

15000 Pa = (1040 kg/m³)(9.80 kg m/s²)h
\frac{15000 Pa}{1040*9.80} = h
1.47 = h

Is that right? TIA

 

[Rick88]

It looks correct.

But do tell your teacher that NO value should be given without its units. (i'm obviously referring to the "1.04" for the specific gravity.)R.

 

[DrMcDreamy]

Its correct! So what would be the usual units for specific gravity? TIA

 

[Rick88]

I would have guessed g/cm^3 as you did.
But purely because the value was close to 1.
(The density of water is 1g/cm^3).

 

[gneill]

I would have guessed g/cm^3 as you did.
But purely because the value was close to 1.
(The density of water is 1g/cm^3).

Specific gravity is unit-less. It's a ratio of densities. That's what makes it "specific".

In most cases it's a ratio of the density of the given substance to the density of water.

 

[Rick88]

Oh, of course.

Thanks for that, gneill.

 

[DrMcDreamy]

Thank you gneill!