# Fluid Mechanics Question: Calculation of kinematic velocity

1. Aug 23, 2009

### thelovemonkey

hey guys im new to the forum... i am a first year civil engineering student trying to do a second year course over this summer holiday. for fluid mechanics i was given this h/w problem. could you please tell me if im correct and if not make explain where i went wrong and how to correct it?

1. The problem statement, all variables and given/known data
at 25 C a fluid has an absolute viscosity of 0.0978 Poise and a Specific Gravity of 0.997. Compute:
a. absolute viscosity in Ns/m^2
b. Kinematic viscosity in SI units

2. Relevant equations

Specific Gravity(SG)= Density of substance(Ds)/ Density of Water(Dw)

Kinematic Viscosity (KV) = Absolute Viscosity in SI units/ Density of Substance(Ds)

1 Poise= 0.1 Ns/m^2

3. The attempt at a solution

A.
if
1 Poise= 0.1 Ns/m^2

then

o.00978 Poise = 0.1 x 0.00978 Ns/m^2 = 0.000978 Ns/m^2

B.

KV= Abs. Viscosity/ Ds

SG= Ds/Dw

Ds= SG x Dw = 1000 kg/m^3 x 0.997 = 997kg/m^3

KV = (0.000978 Ns/m^2)/ (997 kg/m3)

=> KV= 9.8 x 10^-7 Nsm/Kg

2. Aug 23, 2009

### djeitnstine

3. Aug 31, 2009

### thelovemonkey

the lecturer showed us a pretty neat way to handle these units...

Nsm/Kg ->

since N= Kg/m^2
then

units = m^2/ S

very late dont have time to rbeak down