`implies` The force is exerted mutually on two bodies separated by some distance is explained to occur through the field as under:
(1) Every object produces a gravitational field around it, due to its mass.
(2) This field exerts a force on another body lying in this field.
`implies` Intensity of gravitational field : .The gravitational force exerted by the given body on a body of unit mass at a given point is called the intensity of gravitational field `(vecI)` at that point.. It is also known as gravitational field or gravitational intensity.
`implies` Suppose a body of mass M at the origin of coordinate system 0 and a body of mass m= 1 kg is placed at point P having position vector `vecr`
`implies` Gravitation force on bodies of mass m and M,
`vecF=(GMm)/(r^2)hatr`
If `m = 1 kg, vecF = vecI` intensity of gravitation .
`:. vecI=-(GM(I))/r^2hatr" "...(1)`
`implies` Here, force of body of mass M on the body of mass m is toward O, whereas position vector and unit vector is from 0 to P and hence native sign is present in formula.
`implies` And the value of intensity of gravitation
`I = (GM)/r^2 " "...(2)`
`implies` Its unit : `N/(kg)` fe and dimensional formula `M^(0) L^(1) T^(-2)` .
If a body of mass m is put at this point `P_1` the gravitational force exerted by the field on it is `vecF = vec(Im) =- (GMm)/r^2hatr`
`implies` Equation (2) shows that the gravitational intensity due to earth at a point has the same value as the gravitational acceleration (g) at that point.
`implies` Here, gravitational intensity and gravitational acceleration are different quantities but their units and dimensional formula are equivalent.
`implies` For both `I rarr r and grarr r ` graph are same.
