Velocity in Physics Tutorial Part 1

                                           

To know the position of a moving body at any particular point of time, we should know the following parameters:

1.The distance travelled by the body up to that moment of time

2. the direction in which the body is moving.

The distance travelled by a body can be obtained from its speed and the time interval. The speed of the body however does not tell us anything about its direction.

The quantity which gives both the distance travelled and the direction of motion is velocity. 

How is the term velocity defined

Velocity is defined as follows: 

     The displacement of a body per unit time over a short interval is called velocity. Thus,

                            Velocity, v  = Displacement(x)/ Time(t)

                                           V = x/t

The velocity of a body may also be defined as follows:

The distance travelled by a body per unit time in a given direction is called its velocity.

Velocity has both magnitude and direction. So, velocity is a vector quantity. 

Thus, as per definition, the velocity of a body is described as, 

           Velocity (v) = Distance travelled in a specified direction/ Time taken

Now, if a body covers a distance s in time t in a specified direction, the its velocity  (v) is given by, 

V   =  s(in a particular direction)/ t

Please note that both speed and velocity are described by the same equation,

             V = s/ t

The only  difference is that when velocity is calculated using this equation, direction is also mentioned. When speed is calculated, no direction is mentioned.

Units of velocity :- The unit of velocity depends upon the units of distance and time. The SI unit of distance is metre (m) and that of time is second (s). so,

SI unit of velocity = SI unit of distance/ SI unit of time

                                = metre/ second = m/s =  m/s or ms-1 

Thus, the SI unit of  velocity is metre per second (m/s or ms-1)

The CGS unit velocity is centimeter per second, (cms-1)

Velocity may also be expressed in the units of, 

Metre per minute                        m/min                   or                  m min-1

Kilometer per hour                      km/h                      or                   km h-1

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Sashikant