# Energy and Simple Harmonic Motion.

by sailordragonball
Tags: energy, harmonic, motion, simple
 P: 42 A vertical spring with a spring constant of 470 N/m is mounted on the floor. From directly above the spring, which is unstrained, a 0.30 kg block is dropped from rest. It collides with and sticks to the spring, which is compressed by 2.5 cm in bringing the block to a momentary halt. Assuming air resistance is negligible, from what height (in cm) above the compressed spring was the block dropped? ... I tried using KEo + PEo + SPEo = KEf + PEf + SPEf ... but, I can't get anywhere ... ... I found out that the frequency is 18.05hz and it's relative time is .056 seconds - and that's where I'm stuck! HELP!
 P: 42 I made a mistake ... ... I found a formula ... ... initial height = (2*mass*gravity)/(spring constant) ... ... but, there's the 2.5cm differential? ... what do I do? Any help is gladly appreciated.
 P: 938 I'd use conservation of energy like you originally suggested. the 2.5 cm compression of the spring comes in there.
P: 42

## Energy and Simple Harmonic Motion.

I tried that ... but, the lingering the final displacement of 2.5cm is messing me up ... I was wondering ...

(mass*gravity)(initial height + 2.5cm) = .5(spring constant)[(2.5)^2] ...