Is it possible to use Newton's Law of Gravity AND Einstein's Theory of Gravity?

[studentxlol]

to answer this question:

Q) A mass of 100kg is 50m away from a mass of 250kg (from centre of masses). Calculate the gravitational force of attraction between both point masses.

Could I use Einstein's theory of gravity to answer this question using the information given. If so, how would I go about doing it?

 

[Pengwuino]

Since Newton's gravity is just a low-energy limit of Einstein gravity, you technically are using Einstein gravity when you compute F = {{GmM}\over{r^2}} :D

 

[studentxlol]

Since Newton's gravity is just a low-energy limit of Einstein gravity, you technically are using Einstein gravity when you compute F = {{GmM}\over{r^2}} :D

Ok. Give me an example of a high-energy limit and what extra information I need to calculate using Einstein's formula.

 

[Jimmy Snyder]

to answer this question:

Q) A mass of 100kg is 50m away from a mass of 250kg (from centre of masses). Calculate the gravitational force of attraction between both point masses.

Could I use Einstein's theory of gravity to answer this question using the information given. If so, how would I go about doing it?

Einstein's equations don't calculate force. They describe the shape of space-time. Objects move along geodesics of the space-time. No force.

 

[khemist]

So you would actually have to calculate the curvature felt by each object, which would be a kind of sum of the distortions from each mass?

 

[Jimmy Snyder]

So you would actually have to calculate the curvature felt by each object, which would be a kind of sum of the distortions from each mass?

Yes. Probably the easiest calculation is the bending of light as it grazes the sun. There is an excellent book about this and very easy to read. "The Einstein theory of Relativity" by Lieber and Lieber.