Explain the concept of density of objects relative density or specific gravity of water and how an object will behave if placed in water?

Explanation:

Density:

It is define as mass per unit volume.

Units:

SI unit of density is Kg/m3.

Other units are given below,

g/cm3, g/mL , kg/L

Formula:

D=m/v

D= density

m=mass

V=volume

Symbol:

The symbol used for density is called rho. It is represented by ρ. However letter D can also be used to represent the density.

Specific gravity or relative density:

It is the ratio between the density of object and density of reference substance.

Mostly the water is taken as reference and its density is 1 g/cm³.

The value of specific density tell us weather the given substance will sink or float  on reference substance.

For example:

Take the two equal amount of blocks one is made up of styrofoam and one is made up metal. Put these two blocks in to water. The block made up of metal will sink while the other made up of styrofoam will float on the surface of water because of difference in densities. The styrofoam is less denser than water while metal more denser then water.

a mercury barometer is a device that uses the physical properties of mercury in a tube to measure barometric pressure. mercury barometers are used for : -

1. measurement of atmospheric pressure  

2. determining the altitude of a place

3. weather forecasting

4. calibration and checking of aneroid barometers

5. application in fluid mechanics

6. measurement of pressure in aircrafts

7. surface weather analysis

8. preparation of barographs

9. usage in physical sciences like physics, astronomy & chemistry

10. preparation of aircraft altimeters

characteristics of mercury barometer : -

1.used to define and measure atmospheric pressure.

2.on the average at sea level the column of mercury rises to a height of about 760 mm.

3.this quantity is equal to 1 atmosphere.

4.it is also known as standard atmospheric pressure.

5.a barometer in which the weight of a column of mercury in a glass tube with a sealed top is balanced against that of the atmosphere pressing on an exposed cistern of mercury at the base of the mercury column, the height of the column varying with atmospheric pressure.