8. A spring is compressed a distance of 0.15 m from its rest position and held in place while a ball of mass 0.150 kg is placed at its end. When the spring is released, the ball leaves the spring traveling at 9.0 m/s. What is the spring constant?

540 N/m
450 N/m
60 N/m
225 N/m
122.5 N/m

2 answers

I got 225 N/m is this correct?
(1/2) m v^2 = (1/2) k x^2

.15 (81) = k (.0225)

k = 540 N/m