# If the length of a #13 cm# spring increases to #45 cm# when a #4 kg# weight is hanging from it, what is the spring's constant?

##### 1 Answer

Jul 1, 2018

#### Explanation:

We use Hooke's law, which states that,

where:

#F# is the force applied in newtons

#k# is the spring's constant

#x# is the extension in meters

Here we have

So, the spring's constant is: