# Gravitational field strength on Earth

December 12, 2019 A field is something that has a magnitude and a direction at every point in space. Gravity is a good example - we know there is an acceleration due to gravity of about 9.8 m/s2 down at every point in the room. Another way of saying this is that the magnitude of the Earth's gravitational field is 9.8 m/s2 down at all points in this room.

Gravitational field: = /m

where F is the force of gravity.

We can draw a field-line pattern to reflect that, near the Earth's surface, the field is uniform. The strength of a field is reflected by the density of field lines - a uniform field has equally-spaced field lines.

If we zoom out and view the Earth from far away, we get a non-uniform pattern. In fact, the pattern is radial - the lines are further apart as they get further from the Earth, reflecting the fact that g decreases with distance. At every point, though, the field-line pattern shows the direction of the gravitational force that would be experienced by a mass placed at that point.

Source: physics.bu.edu
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##### INTERESTING FACTS ##### Can anyone explain me the derivation of the formula for GRAVITATIONAL FIELD STRENGTH? That is g=GM/r^2? | Yahoo Answers

Not quite sure what you are looking for here.
Newton postulated that the gravitational force (F) between two masses M and m was proportional to the product of their masses and inversely proportional to the square of the distance between their centres of mass (r). Hence:
F [is proportional to] Mm/r²
The next obvious step is to introduce a constant of proportionality G which was determined experimentally, giving us:
F = GMm/r²
When one of the masses (M) is a planet, and m is a relatively small object, we have a special name for the gravitational force between them. We call it the wei…