If a satellite weighs 321 lb. on the earth's surface (R = 4,000 miles), how much does it weigh 12,000 miles above the surface? (Use only one significant digit in the answer)

I got 20 at first then I tried another way and got 40 im sooo confused .

Question

If a satellite weighs 321 lb. on the earth's surface (R = 4,000 miles), how much does it weigh 12,000 miles above the surface? (Use only one significant digit in the answer)

I got 20 at first then I tried another way and got 40 im sooo confused .

anonymous · Answer

GMm/r^2 is the universal equation for gravitational attraction.  Use this with SI units and you should be good.