Calculating Weight of an Astronaut at Different Distances

[nazz]

An astronaut weighs 1000N at the surface of the Earth of radius 6500 km, what his weight will be at 13000 km and 19500km from the centre of the earth?

Do I have to calculate the new value of g at 13000 km using the following?

(G• Mearth) / (Rearth)2
Where:
G = 6.673 x 10-11 N m2/kg2
Mass of the Earth = (5.98 x 1024 kg)

New Re = 13000 km (converted to m)

Then W = M x g

Is there another way of solving it?

 

[Filip Larsen]

You can calculate the answer without knowing the values G and M (or GM). Try write up the equation for the weight W₁ at radius R₁ and the weight W₂ at radius R₂ using GM as you did above and then look at the ratio W₁/W₂.

 

[nazz]

Great answer Filip, thanks