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**What is Gravitational field?**

“The space around the earth in which earth can exert a force of attraction on other bodies is called gravitational field.”A basic fact of the gravitation is that to particles exerts forces on one another.This is a direct interaction between the two particles and is called action at a distance because the two particles interact even though they are not in contact.

Another point of view is the field concept.The gravitational field is a force field.The gravitational field exists around a particle.Whenever another particle enters in the gravitational field ,it will experience an attractive force.The field therefore plays an important role in our thinking about the forces between particles.According to this view we first determine the gravitation field established by the given distribution of particles.Secondly we calculate the gravitational field exerted on another particle placed in its field.When a body is placed in the vicinity of earth,it will experience an attractive force equal to the weight of the body m_{} g_{. }The direction of the gravitational force is towards the center of the earth.The gravitational field becomes weaker and weaker as we go farther and farther away from the earth.

The gravitational field is an example of a vector field ,each point in this field having a vector associated with it.There are also scalar fields,such as temperature field in a heat conducting solid.The gravitational field arising from a fixed distribution of matter is also an example of a static field,because the value of the field at a given point does not change with time.

**What is Gravitational field strength?**

The gravitational field strength at a point is defined as ” Gravitational force per unit mass at that point.”At any place its value is equal to the value of g at that point.Near the surface of the earth,the gravitational field strength is 10 N kg^{-1}. Its formula is given as:

g = F/m_{o}

Where m_{0 }is the test mass.By moving the test mass to various positions,we cam make a map showing the gravitational field at any point in space.We can then find the force on a particle at any point in that field by multiplying the mass m of the particle by the value of the gravitational field g at that point:

F = mg