Density

What?

Density is defined as mass per unit volume It is a fixed property for pure substances.Different materials usually have different densities, so density is an important concept regarding buoyancy, metal purity and packaging.

Formula:
? = m/v

where:

? (rho) is the density,
m is the mass,(in Kg)
V is the volume.(in m³)

The SI unit for density is:

* kilograms per cubic metre (kg/m³)
* grams per cubic centimetre (g/cm³)

Table of Densities

Water ………………………1.00 Glass………………………2.60
Granite……………………...2.650 Bone……………………….1.85
Human Body………………..0.995 Butter……………………...0.94
Ice…………………………...0.917 Carbon…………………….2.60
Kerosene……………………0.800 Chalk………………………2.36
Salt………………………….2.200 Coal………………………..1.50
Sand…………………………2.800 Cork………………………..0.25
Sulfuric Acid………………..1.840 Gasoline……………………0.72

Any object with a greter density than water, sinks in water
and also any object with a lesser density than water , floats in water.

Inertia

What?
Inertia is the resistance of any physical object to a change in its state of motion. It is represented numerically by an object's mass.

The principle of inertia is one of the fundamental principles of classical physics which are used to describe the motion of matter and how it is affected by applied forces.


Inertia is proportional to mass. Big masses resist changing their motion more than smaller masses.

Impact?
An object’s inertia causes it to continue moving the way it is moving unless it is acted upon by an (unbalanced) force to change its motion. An unbalanced force is a net force.

Use of Inertia in real Life..

-Drivers wearing seatbelts for safety when driving to prevent
themselves from falling when braking


-Apple falling from a tree when tree is shaken


-Elephant being unable to move in a zig-zag manner due to its
massive weight