Question

A fat globule of 1.5 µm diameter is rising up in a stagnant skim milk medium of 1005 kg m–3
density and 1.5 cP viscosity. If the density of the fat globule is 915 kg m–3, the steady rising
velocity of the globule in µm s–1 is_____.

Answer 1

Newton's second law of motionpertains to the behavior of objects for which all existing forces are not balanced. The second law states that the acceleration of an object is dependent upon two variables - the net force acting upon the object and the mass of the object.

Answer 2

This question is of milk chemistry.

The concept involved is -

When milk is allowed to stand, fat in it has the tendency to rise. The velocity of fat rise can be given by Stoke's Law -

V = 2/9 * G.r² (ds - df)/N

where V = velocity of fat globule in cm/s

G = force of gravity ( 981 dynes)

r = radius of the fat globule

ds=  density of skim milk

df= density of fat globule

N = viscosity of skim milk

V = 2/9 * 981 * [(1.5/2) *10-4]² (1005 - 915) * 10-3 * / 1.5

V = 218 * 5.6* 10-9  * 9 *10-2  /1.5

V = 7324.8 * 10-11/10-3

V= 7324.8 * 10-8 cm/sec

V= 7324.8 * 10-8 * 10³ micro meter/sec

V = 0.073 micro meter/sec

So, the answer is 0.073 micro meter/sec.