If the length of a 45 cm45cm spring increases to 63 cm63cm when a 7 kg7kg weight is hanging from it, what is the spring's constant?

1 Answer
Jun 11, 2018

Approximately 381.1381.1 newtons per meter.

Explanation:

We use Hooke's law, which states that,

F=kxF=kx

where:

  • FF is the force applied in newtons

  • kk is the spring constant in "kg/s"^2kg/s2 or "N/m"N/m

  • xx is the extension in meters

Here, the force is the weight of the object, which is equal to:

7 \ "kg"*9.8 \ "m/s"^2=68.6 \ "N".

The spring constant is then:

k=F/x

=(68.6 \ "N")/(0.63 \ "m"-0.45 \ "m")

=(68.6 \ "N")/(0.18 \ "m")

~~381.1 \ "N/m"