Field
The temperature has a definite value at every point in the room in which we are sitting. We can measure the temperature at each point by putting a thermometer at that point and then we could represent the temperature distribution throughout the room either a mathematical function say, T(x,y,z ) or else with a graph plotting the variation of 'T'. Such a distribution of temperature is called a temperature field.
In a similar way we could measure the pressure at points throughout a fluid and so obtain a representation for the pressure field. If the pressure varied then field are called scalar fields, because temperature T an pressure P are scalar quantities. If the temperature and pressure do not vary with time, they are also called static field and might be represented by a function T (x,y,z) and (t).
We introduce the gravitational field'g', the gravitational force ' F ' per unit mass ' m '
This field is also a vector field and in addition is usually static, when the distribution of mass of the gravitating body that is the sure of the field remains constant. near the surface of the earth, and for points not too far a part it is also a uniform field that ' g' is the same ( in direction well as magnitude ) for all points.
The above equation tells us that the acceleration is equal ( in magnitude and direction ) to the gravitational field ' g ' at that point. Before the concept of field became widely accepted, the force b/w gravitating bodies was thought of as a direct and instantaneous interaction. this view called action at a distance was also used for electromagnetic forces. In case of gravitation, it can be represented schematically as
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