# If the length of a #29 cm# spring increases to #63 cm# when a #15 kg# weight is hanging from it, what is the spring's constant?

##### 1 Answer

I calculate

#### Explanation:

The equation we use to calculate the force constant of a spring is Hooke's Law ,

To make it simpler, I'm going to ignore the negative sign (so

We need to rearrange this equation to make

The value of

The value of

We will use the value in metres, as it's the proper SI unit for distance. Now we can substitute these values into the rearranged equation to find the spring's constant!