Fluids

Fluids are one of the most important part of universe.They constitute much part of our daily lives and we are surrounded by them.

Fluids are static as well as dynamic,molecularly static is also dynamic,as per the experiments of robert brown in 1827 maybe,who was related to biology,later on albert einstein explained the effect,the brownian movement-zig zag pattern movement or let's say path followed.

Fluids have many properties.There are two kinds of fluids,which are as follows:-

1.Gaseous

2.Liquids

Both have there own respective properties and nature and features.

Both occupy volume and they have density.

The major difference is volume of liquids is constant,shape is variable,while gaseous can be compressed,so neither there volume neither shape is constant,but is a variable,which can be changed.

Fluids are so called because they possess fluidity,which simply means they can flow.

Now gaseous i believe can flow faster under conditions than liquids because liquids are bulky as compared to gaseous while the latter ones are very light.Now,it is also true that liquids flow faster than gaseous in specific conditions.

Density of gaseous is less a than liquids as gaseous generally tend to extend,other than when pressure is applied and gas is forced to minimize and it's volume is also reduced.

Now,with that density will increase during compression of gas and density will decrease during relaxation of gas as density is inversely proportional to the volume of gas.

Fluids both liquids and solids possess fluid friction called as viscosity just as surface has friction and it's counterparts.

Density of a substance is defined as the mass per unit volume.Density of a sunstance for a homogenous substance depends upon three parameters,so we have density=f(x,y,z)

So ,density in this case is function of three parameters.Now,when position is changed for homogenous substance,the volume does not change,so parameters remain constant,so is density.

S.I. unit of density is Kg/cubic metre

Dimensional formula will be M/L.L.L

C.G.S. unit will be g/cubic centimetre

Specific gravity is defined as the ratio of density of substance to the density of water at 4 degree celsius temperature,which is 1000 kg/cubic metre.

It has no S.I. units and C.G.S. units,

It is a dimensionless quantity,since it is the ratio of density to density.

Problems

P1.If we have 50 g of gasoline in 100 cubic centimetre of water,then find specific gravity and density of gasoline?

Density=Mass of gasoline/volume of water

Density(gasoline)=50/1000/100/1000000

Density will be 500 kg/cubic metre

Now,for specific gravity two methods are available.

First method

Sp.gravity=500/1000=0.5

This one is directly from definition of specific gravity.

Second method

Sp.gravity=Mass of gasoline/Mass of water

Quick one.

Now,if volume of water is 20cubic centimetre,then mass is considered as 20g,in this case mass of water is 100g

So specific gravity=50/100=0.5

Same answer.