Introduction of mechanics-2 (Quantity and Unit)

There are two type of quantity which we see:-

1. Scalar quantity
2. Vector quantity

• Scalar quantity:-A scalar quantity one which has only magnitude in it and it has no direction.

          Example:-Mass,Volume,Time,Speed,Distance,Work done etc.

• Vector quantity:-A vector quantity is one which has both magnitude and direction.It is represented by arrow.

         Example:-Weight,Velocity,Acceleration,Displacement,Force etc.

Representation of vector quantity:-

If both have same magnitude but different direction;

Example:-

Resultant/resolution of vector quantity:-

X-component of force vector

Y-component of force vector

Addition of vector:-

Unit:-A standard magnitude or quantity used for measurement is known as a unit.It is the basic think to define measurement.

1. Fundamental units:-The units adopted for measuring the fundamental quantities like length,mass and time are called fundamental units.
2. Derived units:-The units which are derived from fundamental units are called derived units.

Flow chart of system of units:-

1. F.P.S. system:-In this system the unit of length,mass and time are foot,pound and second respectively.
2. C.G.S. system:-In this system the unit of length,mass and time are centimetre,gram and second respectively.
3. M.K.S. system:-In this system the unit of length,mass and time are metre,kilogram and second respectively.
4. S.I. units or international system of units:-S.I. is based on seven basic units and two supplementary units.

The seven basic units are:-

The two supplementary units are:-

Dimension:-

Example:-