Question

1. Now we’ll find the mass of the three “Mystery Weights” That are provided. Since we now know the spring constant (or at least an average) we can work backwards to find the mass. Rearranging Hooke’s Law, we have:
   

And using the weight in place of force, we get:

So we’ll multiply the spring constant you found above by the displacement, then divide that by gravity to get the mass of our “mystery masses”. Fill in the data table below, being careful to use meters and kilograms.

Answer 1

If you know the spring constant of a spring, you can find the mass of any object by just hanging the object from the spring and let the spring stretch and come to rest.

Now measure the amount by which the spring has extended from initial position. This will be displacement 'x'

then

F = kx

where k is spring constant which you already know and we have just found x.

then

solve for F.

this is the force ( weight ) of object

just divide by 9.8 to get the mass of the object.