# An object with a mass of 4 kg is hanging from a spring with a constant of 3 (kg)/s^2. If the spring is stretched by  10 m, what is the net force on the object?

$\sum F = {F}_{k} - m g = 30 - 40 = - 10 N$
First let's round up gravity $g \approx 10$
$\sum F = {F}_{k} - m g = 30 - 40 = - 10 N$