# Springs & Energy

Tags:
1. Dec 10, 2014

### Quantum Fizzics

1. The problem statement, all variables and given/known data
Hello, I'm having an issue with a question I have all the numbers and everything but I cant quite get the answer correctly and its very frustrating..

A mass, m is held at UEP of a vertical spring constant k & allowed to fall. Calculate:
a) The maximum stretch(max bottom)
b) The amplitude of vibration

2. Relevant equations
PEg + PEe + KE= PEg' +PEe'+ KE'
h = xo = mg/k

3. The attempt at a solution
I've solved the amplitude of vibration already im just stuck at part a) I really do not know how start please help thanks

2. Dec 10, 2014

### haruspex

You've quoted the right equations - just fill in the blanks: in terms of the desired unknown, what are the loss in gravitational PE, the gain in spring PE, and the change in KE?

3. Dec 11, 2014

### Maged Saeed

I'm not sure but I think I think that depends on the spring ,,
If it is in equilibrium after falling we will use the laws of conservation of energy ,
If it is not "say it is oscillating" we shall use newton second law , because in oscillation , we can't specify the final and initial positions of the string [it would go back farther than it's initial position when it's allowed to fall]

I'm I right ??

4. Dec 11, 2014

### haruspex

No, it's not the stretch at equilibrium we want, it's the maximum stretch, and that occurs once in each oscillation.