# Bulk modulus of Liquid helium and first sound

Does anyone know where to find the bulk modulus of liquid helium ?

I've been looking all over the internet but everywhere I get N/A. Any tips ?

I'd need it to estimate the speed of first sound in liquid helium which is given by:

$c_1=\sqrt{\left.\frac{\partial p}{\partial\rho}\right|_\sigma}$

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A Google books search for "bulk modulus of liquid helium" turned up this result: Helium, edited by Paul Muljadi. On page 7, you will find the value of the bulk modulus as on the order 50 MPa. There is a reference linked to this value, but it is not part of the free preview, so I cannot tell you what it is.