How do I Taylor expand the gravitational field in terms of h/R <<1?

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SUMMARY

The discussion focuses on performing a Taylor expansion of the gravitational field \underline{G}(\underline{r}) in the limit of h/R << 1, where h is the height above Earth's surface and R is the Earth's radius. The gravitational field is expressed as \underline{G}(\underline{r})=\frac{-GM(R+h)}{(R+h)^3}\underline{e}_z, which simplifies to \underline{G}(\underline{r})=\frac{-GM}{R^2}(\frac{h}{R}+1)^{-2}\underline{e}_z. The key takeaway is that the gravitational force on a mass m can be approximated as \underline{F} \approx mg\underline{e}_z, with g expressed in terms of R and M, the mass of the Earth. The first correction to the gravitational force, dependent on h, is also sought.

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Students of physics, particularly those studying classical mechanics and gravitational theory, as well as educators seeking to explain gravitational field concepts through Taylor expansions.

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Homework Statement


Consider the position vector of a mass m at height h above the Earth's surface to be \underline{r}=(R+h)\underline{e}_z where R is the radius of the Earth.
Make a Tylor expansion in h/R <<1 of the gravitational field
\underline{G}(\underline{r})=\frac{-GM\underline{r}}{r^3}
to show that the gravitational force on a mass m can be written as \underline{F} \approx mg\underline{e}_z giving an expression for g in terms of R and M, the mass of the Earth.
Find the first correction (h-dependent) to the gravitational force.

Homework Equations

The Attempt at a Solution


I am having trouble understanding how to expand the function in h/R<<1.

We can rewrite \underline{G}(\underline{r})=\frac{-GM(R+h)}{(R+h)^3}\underline{e}_z which then can then be expressed as \underline{G}(\underline{r})=\frac{-GM}{R^2}(\frac{h}{R}+1)^{-2}\underline{e}_z
I am not sure how to proceed with the expansion.
Any explanation will be appreciated.
 
Physics news on Phys.org
Let ##x = h/R##. You need to make a Taylor series expansion of the function ##f(x) = (x+1)^{-2}##.
 

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