Physics Class 11 Chapter 10. Mechanical Properties of Fluids | Page 5

Density of a Mixture of Substances
When two liquids of mass m1 and m2 having density p1 and p2 are mixed together then density of mixture is p = m1 + m2 / ( m1 / p1 ) + ( m2 + p2 )
= p1p2 ( m1 + m2 ) / ( m1p2 + m2p1 )
When two liquids of same mass m but of different densities p1 and p2 are mixed together then density of mixture is
p = 2p1p2 / p1 + p2
When two liquids of same volume V but of different densities p1 and p2 are mixed together then density of mixture is
p = p1 + p2 / 2 Density of a liquid varies with pressure p = po [ 1 + Δp / K ]
where , po = initial density of the liquid , K = bulk modulus of elasticity of the liquid and Δp = change in pressure
Viscosity
The property of a fluid by virtue of which an internal frictional force acts between its different layers which opposes their relative motion is called viscosity .
These internal frictional force is called viscous force .
Viscous forces are intermolecular forces acting between the molecules of different layers of liquid moving with different velocities .