Finding mass of spring from time period.

amk_dbz

As the title suggests, there is a practical in which we have to find mass of the spring (m*) having a block of mass M attached to bottom, from GRAPH of time period (T)^2 against M.
Here's what the practical handbook says:
T^2= [16{(pi)^2}(R^3)N][M+(m*/3)] / [(r^4)n]
there is no reference to what is N,n,R,r
What they do next is to plug in T=0
therefore, M+(m*/3)=0
=> m*/3=-M
Considering magnitude, m*=3(x intercept)

The last part makes some sense but, where does the formula come from?

Thank you! (Sorry for being messy)

andrien

the formula will come when you will consider kinetic energy of spring(it has mass).see here
http://en.wikipedia.org/wiki/Effecti...93mass_system)