Why g varies on the surface of the earth

You can use the following equation to calculate g at a certain latitude, accounting for both of these effects:. You can use this to find the apparent value of g at a location in the United States or in Argentina. To get the gravitational force, also called weight, multiply g by the mass of the object you're interested in. Be sure to use consistent units.

That equation assumes you're at sea level, but if you want to account for the effect of altitude when you go up in a plane you can use this additional equation:. The effect of changes in altitude due to actual elevation of the land is more complicated, because in addition to raising you farther from the center of the Earth the land also provides an additional source of gravity. Whether the local g goes up or down with surface altitude depends on how dense the Earth's crust is in that area.

After you calculate the difference in local gravitational acceleration between the United States and Argentina, let us know if you think of any ways it might affect the people living there. Computing gravity at five points would take 1 second on an ordinary PC, but the team used a supercomputer to do the whole lot in three weeks.

The model pinpoints more extreme differences in gravitational acceleration than previously seen. Standard models predict a minimum gravitational acceleration of 9. These differences mean that in the unlikely event that you found yourself falling from a height of metres at each point, you would hit the surface in Peru about 16 milliseconds later than in the Arctic. When discussing the acceleration of gravity, it was mentioned that the value of g is dependent upon location.

There are slight variations in the value of g about earth's surface. These variations result from the varying density of the geologic structures below each specific surface location. They also result from the fact that the earth is not truly spherical; the earth's surface is further from its center at the equator than it is at the poles.

This would result in larger g values at the poles. As one proceeds further from earth's surface - say into a location of orbit about the earth - the value of g changes still. To understand why the value of g is so location dependent, we will use the two equations above to derive an equation for the value of g.

First, both expressions for the force of gravity are set equal to each other. Now observe that the mass of the object - m - is present on both sides of the equal sign. Thus, m can be canceled from the equation. This leaves us with an equation for the acceleration of gravity. The above equation demonstrates that the acceleration of gravity is dependent upon the mass of the earth approx.

If the value 6. And of course, the value of g will change as an object is moved further from Earth's center. For instance, if an object were moved to a location that is two earth-radii from the center of the earth - that is, two times 6. As shown below, at twice the distance from the center of the earth, the value of g becomes 2.