Determine an expression for the period of motion.

[Doc Al]

The mass should cancel and thus not appear in your final version.

 

[borobeauty66]

What I meant by saying the equation was wrong was in your #3 post you put the equation wrong. In actual fact the mass should come after the division. Thus

and not

which would make k = 4Gπρ and not k = 4Gπρm

Surely this means the m isn't canceled out at the end?

 

[Doc Al]

What I meant by saying the equation was wrong was in your #3 post you put the equation wrong. In actual fact the mass should come after the division. Thus

and not

Those expressions are identical! (Except for the unneeded unit vector.) For the same reason that (a/b)x is the same as (ax/b).

 

[borobeauty66]

Those expressions are identical! (Except for the unneeded unit vector.) For the same reason that (a/b)x is the same as (ax/b).

ah ok!

thats what confused me, i thought they were different.