# If the length of a #13 cm# spring increases to #40 cm# when a #7 kg# weight is hanging from it, what is the spring's constant?

##### 1 Answer

Oct 22, 2016

I got:

#### Explanation:

Consider that at equilibrium the elastic force

We get:

(eleasic force upwards and weight downwards)

The displacement

(I changed into meters)

rearranging we get: