Speed in Physics

                                                              SPEED
Today We are going to Discuss about Speed. First of all we have a question what is Speed.


Speed :- The speed of a moving body tells us how fast the body is moving. Thus, The Speed of a body describes the rapidity of its motion.

                                                            Or,

The time rate of covering the distance by an object is called its Speed.


How is Speed defined.

The Speed of a body describes the rapidity of its motion at a particular moment of time during the course of motion. The Speed of a moving body might change from time to during the course of its motion. For fast moving bodies, such changes in Speed will be quite rapid. However if the Speed of a moving body remains nearly constant over a small interval of time, then that Speed can be taken as the Speed of the body at that point of time.

The Speed of a moving body is defined as follows:

  • The distance travelled by a body per unit time over a short interval of time is called its speed.

  Thus, the Speed of a moving body may be expressed by the relationship,

      Speed = Distance travelled in a short interval of time / Time interval

  • Speed is a scalar quantity. Speed has only magnitude. If a body covers a distance s in time t, then its Speed (v) is given by,
                                                                  V = S / t
  • Units of Speed. Speed is expressed in term of distance travelled and time tamen. So, the unit of Speed depends upon the units of distance and time. Thus,

                            Unit of Speed = Unit of distance / Unit of time

The SI units of distance and time are metre (m) and second (s) respectively. Therefore,
                         SI unit of Speed = metre / second    
                                                    = m / s or ms−1
      
    
  • Thus, the SI unit of Speed is metre per second, which is written as m / s or, ms−1 .

         The CGS unit of Speed is centimetre per second. (cm s−1 )


  • However, Speed can be expressed in many different units, such as,

Centimetre per second                              cm / s      or        cm s−1

Metre per minute                                         m / min      or  m min−1

Kilometre per hour (km p h )                      km / h        or    km h−1

  • The speed of fast moving bodies viz, car, scooter, aeroplane, etc. are generally expressed in units of kilometre per hour (km / h).

  • The speed of slow moving bodies are commonly expressed in the units of centimetres per second (cm / s ) or metres per minute (m / min ).




  • Thank you(Sashi Kant)








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