elasticity in colloids (gels, jellies)

[elaine216@hotmail.co]

I have a question on finding elasticity of colloids.

I am using Ultrasonics testing on testing the different elasticity of gelatine with different concentrations of additives, ie, salt, sugar.

From the ultrasonics data, I calculated the attenuation coefficient and the velocity (speed of sound) of the gelatine.

there is an equation related to the modulus of elasticity:

V= sqrt (C/P)

where V is the speed of sound, C is the elastic constant and p is the density.

however, I dont know the denisty of the sample I tested. So, is there other ways to calcuate the density with the attenuation coef and velocity? or is there another formula that can solve my problem?

Please help....:(

[HallsofIvy]

It should be simple to calculate the density of your sample- I suspect that "additives" like salt, sugar, etc. won't noticably affect the average density so you might get away with just taking a sample of your gelatin, finding its volume and mass and dividing!

I would recommend making up a new batch with the additives and doing the same just to be sure that the density hasn't changed significantly.