# An object with a mass of 8 kg is hanging from a spring with a constant of 9 (kg)/s^2. If the spring is stretched by  1 m, what is the net force on the object?

Apr 28, 2018

Recall,

${F}_{\text{s}} = - k \Delta x$, and

$\Sigma F = m a$

When a spring is stretched, it has elastic potential energy. In this situation, it is working against gravity in the opposite direction (which we'll assume is positive).

Hence,

$\Sigma F = k \Delta x - m g \approx - 70 \text{N}$

is the net force on the object.