Question

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?

Answer 1

`sumF = F_k - mg = 30 - 40 = -10N`

Explanation:

First let's round up gravity `g ~~ 10`
Take at the free body diagram a quick check indicate there
An inbalance of forces, there is more weight and the spring have stretched enough to balance the weight. The net force is exactly equal to the inbalance:
`sumF = F_k - mg = 30 - 40 = -10N`