Physics - springs?

Question

A 2 kg mass hangs motionless from a partially stretched spring having a spring constant of 203 N/m. What is the magnitude of the force (in N) that would be required to pull the mass down by an additional 4 cm?

Answer 1

weight = k x

mg = k x

mg + Mg = k (x+0.04)

eliminate (x)

mg + Mg = mg + 0.04k

additional Force = Mg = 0.04 k = 203*0.04 = 8.12 N

you need to hang (M = 8.12/9.8 = 828.57 grams) additionally