physics problem — fluids — need clarification on work done?
Blood plasma flows from a bag through a tube into a patient’s vein, where the blood pressure is 10 mmHg. The specific gravity of blood plasma at 37°C is 1.03. What is the minimum elevation the bag must have so the plasma flows into the vein?
Ive used the formula
P = P0 + density * g * h
10mmHg = 1.03 kg/m^3 * 9.81N/kg * h
is this correct and solve for h?
Tagged with: blood plasma • blood pressure • density • elevation • p0 • specific gravity of blood
Filed under: how to lower blood pressure
Yes and No. There are still a few things you need to fix with your equation. P0 represents the ambient pressure which we assume to be at sea level = 101,325 Pa (or N/m^2).
The specific Gravity is a factor is used to determine the density of blood.
SG = density of substance / density of water. Since the density of water is 1000 kg/m^3, you will find the density of blood to be 1030 kg/m^3.
Also your gravity units should be m/s^2 and you need to convert 10mmHg into Pascals (Pa).
Since 1mmHg is approximately 133.32 Pa
10mmHg is approximately 1333.20 Pa (or N/m^2…same thing)
Now keep in mind the equation you use is
TOTAL PRESSURE = Absolute Pressure + density*g*h
Your equation should actually be written:
1333.20 Pa = 0 + 1030N/m^2 * 9.81 * h