A little help/direction would be very helpful:
The needle of a syringe has a diameter $d=0.6mm$ and its length is $l=2cm$. The water flow forced in the needle is $Q=10^{-7} m^3 s^{-1}$
Assuming laminar flow, calculate:
- The average speed of water
- What is the pressure drop necessary to have such a flow I think I'm OK with the 1: $Q=S×V$ so:
$$V=Q/S=10^{-7}/( 6×10^{-3} × 6 ×10^{-3}) = 8.84×10^{-4} m s^{-1}$$
2/ For this one I assume I have to use Poiseuille equation:
$$\Delta P = \frac{8\mu LQ}{\pi R^4}$$
but I don't know how to do as I don't have the dynamic viscosity of the water ($\mu$). I don't know if I suppose to know this value (as it depend on temperature I presume?) or if I have to / can express the pressure drop without knowing this value.
Can someone help me/push me a little in the right direction?