Conservation Of Energy--Mass-Spring System

On this case, we will talk about the spring, mass and energy. The spring's is 0.044kg.
We use two different mass to measure the spring constant of spring.

Follow the date, when the spring hand 0.05kg, the distance is 0.05m and the force is 1.23N. because the hook's law, F=kx, we got the k is 16N/m.

On the second case, we let the spring hand 0.2kg. then the distance of spring is 0.2m and F is 3.68N, the we calculate that the K is 16.25N/m. it is almost closed.