If an object's weight on the surface of the Earth is w, compare the weight when the object is 1/3 of the Earth's radius away from the Earth's center.
Assume uniform density and ignore Earth's rotation.

Question

If an object's weight on the surface of the Earth is w, compare the weight when the object is 1/3 of the Earth's radius away from the Earth's center. 
Assume uniform density and ignore Earth's rotation.

irishboy123 · Answer

do you have the underlying equation - Newton's Law of Gravitation?  Can you recite it here?

sh3lsh · Answer

My thoughts: 
Normal object is 
$$F= \frac{ G m_{e} m  }{ r ^{2} } = w$$

Now object is 
$$F= \frac{ G m_{e} m  }{ (\frac{ r }{ 3 }) ^{2} } = 9w$$

irishboy123 · Answer

ok

but now that is it inside the earth, there is a lot of gravity pulling it outwards!

you're allowed to assume symmetry.

sh3lsh · Answer

Why is it pulling it outwards?
Are my equations correct?

irishboy123 · Answer

|dw:1428176686919:dw|

ALL that mass is pulling you out.