Learn with Rashmi Class-8

Speed is the rate of change of distance.It is a scalar quantity.

Distance          The distance covered by a moving body is the length of path covered by the body. In SI system,             distance is measured in metre (m). It is a scalar quantity as it has only magnitude but no direction.  Displacement             The shortest distance covered by a moving body in a fixed direction is called displacement. In SI             system, it is measured in metre (m). Displacement is a vector quantity as It has both magnitude                and direction.

 

 1 second is defined as (1/86400) part of one solar day.

  The duration between any two events is called time.

 

 The weight of a body is defined as the force with which it is pulled towards the center of the earth or a planet.

 

 

 

 

 The mass of a body is the total amount of matter contained in it.

 

 

 Those units which are formed by the combination of two or more fundamental units are called derived units. 

 

 Those units which are independent of each other are called fundamental units.

 The standard quantity which is used for the comparison of an unknown physical quantities is called unit.

 

 

  Those physical quantities which are derived from the fundamental physical quantities are called derived physical quantities.

 

Those physical quantities which are independent of each other are called fundamental physical quantities.There are seven fundamental physical quantities.

  -The quantities which can be measured is called physical     quantities.Length,Breadth,Time,Area,Volume,etc can be measured so it is called physical      quantities.

  To find the accurate quantity of the object by using standard measurement device. To bring uniformity of measurementsystem. To buy and sell food/groceries. To cook food.

The comparison between a known standard quantity and an unknown standard quantity is called Measurment.