Weight Away from Earth's Surface [CONCEPT-NO MATH]

[SigFig]

Homework Statement

When calculating weights away from Earth's surface, for example:

At 6.38x10^3 km away from Earth's surface a spacecraft s weight is d=rE+rE or 2rE
Then F=(1/4)(SpaceCraftWeight)

What I don't understand is why the distance is rE+rE?

Or when 1.28x10^4 km away
d=rE+2rE or 3rE ?

I'm also assuming since F=mAmB/d^2
That's why F= (1/(x^2)(W) ?

 

[Dick]

Homework Statement

When calculating weights away from Earth's surface, for example:

At 6.38x10^3 km away from Earth's surface a spacecraft s weight is d=rE+rE or 2rE
Then F=(1/4)(SpaceCraftWeight)

What I don't understand is why the distance is rE+rE?

Or when 1.28x10^4 km away
d=rE+2rE or 3rE ?

I'm also assuming since F=mAmB/d^2
That's why F= (1/(x^2)(W) ?

Because the d in F=mAmB/d^2 is the distance from the center of the earth. Not the distance to the Earth's surface.