# Properties of bulk IV

Critical velocity:- It is that velocity of liquid flow, upto which the flow of liquid is streamlined and above which its flow becomes turbulent. Critical velocity of a liquid (Vc) flowing through a tube is given by

Where ρ is the density of liquid following through a tube of radius r and ƞ the coefficient of viscosity of liquid

Reynold’s number:- It is a pure number which determines the nature of flow of liquid through a pipe.
Quantitatiively Renold’s number
Where ƞ is coefficient of viscosity of liquid , ρ is density of liquid D is the diameter of the tube, Vc is critical velocity
For stream line flow, Reynold’s number < 2000
For turbulent flow, Reynold’s number > 3000
For uncertain flow, 2000 < Reynold’s number < 3000

Theorem of continuity:- If there is no source or sink of the fluid along the length of the pipe, the mass of the fluid crossing any section of the pipe per second is always constant
Mathematically
It is called the equation of continuity
For in compressible liquid ρ1 = ρ2

Therefore the equation continuity becomes
Bernoulli’s theorem:- It states that for an in compressible non-viscous liquid in steady flow, the total energy i.e. pressure energy, potential energy and kinetic energy remains constant its flow.
Mathematically

Application of Bernoull’s theorem

(i) Working of Bunsen burner
(ii) Lift of an air foil
(iii) Spinning of ball (Magnus effect)
(iv) Sprayer
(v) Ping pong ball in air jet.

Toricelli’s theorem/speed of efflux:- It states that the velocity of efflux i.e. the velocity with which the liquid flows out of an orifice (i.e. a narrow hole) is equal to that which is freely falling body would acquire in falling through a vertical distance equal to the depth of orifice below the free surface of liquid.
Quantitatively velocity of efflus
Venturimeter:- It is a device use to measure the rate of flow of liquid. Venturimeter consists of a wide tube having a constriction in the middle. If a1 and a2 are the areas of cross section of the wide end and the threat, p1 and p2 are the pressure of liquid, then velocity of the liquid entering at the wide end is given by
Surface tension (T):- It is the property of a liquid by virtue of which, it behaves like an elastic stretched membrane with a tendency to contract so as to occupy a minimum surface area
Mathematically T = F/l
S.I Unit is : Nm-1
Dimensional formula : ML0T-2
Surface Energy : The potential energy per unit area of the surface film is called the surface energy.

Surface tension is numerally equal to surface energy

Excess of pressure inside a drop and double:-

There is excess of pressure on concave side of a curved surface
1. Excess of pressure inside a liquid drop = 2T/R
2. Excess of pressure inside a liquid bubble = 4T/R
3. Excess of pressure inside an air bubble = 2T/R, Where T is the surface tension , R = radius of liquid drop

Angle of contact:- The angle which the tangent to the free surface of the liquid at the point of contact makes with the wall of the containing vessel, is called the angle of contact
For liquid having convex meniscus, the angle of contact is obtuse and for having concave meniscus, the angle of contact is acute.

Capillary tube:- A tube of very fine bore is called capillary tube
Capillarity:- The rise or fall of liquid inside a capillary tube when it is dipped in it is called capillarity
Ascent formula:- when a capillary tube of radius ‘r’ is dipped in a liquid of density s and surface tension T, the liquid rises or depresses through a height,
There will be rise a liquid when angle of contact θ is acute. There will be fall in liquid when angle of contact θ is obtuse.

Click here to view complete Chemistry Free Study Materials and Notes for NEET Preparation

Click here to view complete Physics Free Study Materials and Notes for NEET Preparation

Click here to view complete Biology Free Study Materials and Notes for NEET Preparation