fluid pressure difference

SoccaCrazy24

A patient is given an injection with a hypodermic needle 3.2 cm long and 0.25 mm in diameter. Assuming the solution being injected has the same density and viscosity as water at 20°C, find the pressure difference needed to inject the solution at the rate of 1.5 g/s.

ok I have the equation V = [(P1-P2)(pi*r^4)]/(8*n*L)
(P1-P2)= pressure difference
r= .000125 m
n= .0010055
L= .032 m
I do not know how I am suppose to transform 1.5g/s to m/s because im unsure of how to transfer grams to meters.... once i get that I can find the difference in pressure...

In a similar problem with diameter being .28mm the answer came out to be 320kPa... help???

mezarashi

Pressure energy is converted into kinetic energy.
To convert volume flow into velocity, you can consider:

[tex]\dot{V}= A\cdot v[/tex]