**FUNDAMENTAL AND DERIVED UNITS :**

In mechanics, there are three basic units or fundamental units and they are length, time and mass. Derived units are then represented where dimensional representatives are necessary.

**FUNDAMENTAL UNITS:**

Fundamental unit are the basic building block in science and there are a few of this fundamental physical quantities.

**DERIVED UNIT **

This simply is the combination of the S.I. basic unit that is dimension to derive the exact form of physical equation and we can obtain other useful unit, these are called derived unit. The unit of volume is obtained by multiplying three lengths, which is called cubic meter. Density is the ratio of mass and volume. Then the S.I. unit of density is which is called kilogram per cubic meter. Speed is the ratio of distance and time, so therefore the unit is which is called meter per seconds. Other derived units are listed below:

**Examples**:

**FORCE**: This is the product of mass and acceleration

F = ma

Where: m = mass = M

a = acceleration = L/T² ..……………i

**MOMENTUM**: This is the product of mass and velocity

P = MV

Where: m = mass = M

V = M/S ……………………….ii

**PRESSURE**: This is force per unit area

Where: F = force = as in (i) above

A = area = L² ….…………….iii

**VOLUME**: is the quantity of three-dimensional space enclosed by some closed boundary.

V =L³……………………….iv

**DENSITY**: This is mass per unit volume

Where: M = mass = M

V = volume = L³……………….v

**VELOCITY**: This is distance per unit time

Where: D = Distance = L

T = Time = T ………………………….vi

**ACCELERATION**: This is velocity per unit time

Where: V = velocity = as in (vi) above

T = time = T ……………………………vii

**IMPULSE**: This is the product of force and time

Where: F = force = as in (i) above

T = time = T ……..…………viii

The Penalty for Ignorance is Lack