# Wolfram Mathematica

## Examine Variations in Earth's Gravitational Field

The gravitational field on the surface of the Earth varies due to inhomogeneities in the matter density and the non-spherical shape of the Earth.

This is the standard average value of the field on the surface of the Earth.

In[1]:=
```g = UnitConvert[Quantity[1., "StandardAccelerationOfGravity"], "SIBase"]```
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Compute the difference between an array of values for the gravitational field over the US and the standard average value.

In[2]:=
```data = GeogravityModelData[Entity["Country", "UnitedStates"], "DownComponent"] - g```
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Plot the data on a map of the US.

show complete Wolfram Language input
In[3]:=
```plot = ListContourPlot[data, Frame -> False, PlotRangePadding -> 0, ColorFunction -> "TemperatureMap"]; Legended[GeoGraphics[{GeoStyling[{"GeoImage", plot}, Opacity[0.8]], Polygon[Entity["Country", "UnitedStates"]]}], BarLegend[{"TemperatureMap", MinMax@Flatten[QuantityMagnitude@data]}]]```
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