physics
posted by Justin .
A spring has a length of 0.190 m when a 0.300 kg mass hangs from it, and a length of 0.750 m when a 2.80 kg mass hangs from it.
(a) What is the force constant of the spring?
(b) What is the unloaded length of the spring?

F=kx
.3*g=k(.190u)
2.80g=k(.750u) u is the unstretched length.
solve for k. 
What is the unstretched length?