# If the length of a 46 cm spring increases to 57 cm when a 8 kg weight is hanging from it, what is the spring's constant?

$\text{713 N/m}$
$F = k \Delta x$
k = F/(Deltax) = (mg)/(Deltax) = ("8 kg × 9.8 m/s"^2)/("0.57 m - 0.46 m") = "713 N/m"