Acceleration Due to Gravity on earth

[eagles12]

Homework Statement

At what altitude above the Earth's surface is the acceleration due to gravity equal to g/3?

Homework Equations

ag=G Me/(Re+H)^2

The Attempt at a Solution

I solved for H and got H=√3 Re-Re
using this i got 17*10^6
but it is saying this is not correct

 

[gneill]

Homework Statement

At what altitude above the Earth's surface is the acceleration due to gravity equal to g/3?

Homework Equations

ag=G Me/(Re+H)^2

The Attempt at a Solution

I solved for H and got H=√3 Re-Re
using this i got 17*10^6
but it is saying this is not correct

Can you show the details of your calculation? What value did you use for Re?

 

[D H]

I solved for H and got H=√3 Re-Re
using this i got 17*10^6

17*10^6 what? Distance isn't just a number. It has units. What are the units of this number 17*10^6, what units is the answer supposed to be in, and what value did you use for the radius of the Earth?

 

[eagles12]

for re i used 6.37*10^6m
the answer is also sopossed to be in meters

i started with ag=g Me/(Re+H)^2
then plugged in 1/3*9.8=G Me/(Re+H)^2
I reduced that to ag=1/(Re+H)^2=1/3(1/Re^2)
from there i got
(Re+H)^2=3Re^2
Re+H=sqrt(3)*Re
H=sqrt(3)Re-Re

 

[gneill]

Your derivation looks okay, so you must be having finger problems with the calculator