# Homework Help: Spring & mass

1. Mar 9, 2014

### Emilsen

Hi,
I'm a mechanical engineer from Norway who has an work related query.
Please see the attached picture describing the problem.

I'm trying to figure out how heigh mass 1 travels if mass 2 is quick released when being suspended in a spring. I'm also trying to figure out a the maximum acceleration, but thats 2. priority.

I have tried to work out an answer my self, but I don't think it's correct.
The thing I can't get my head around is how to calculate the height mass 1 travels above it's equilibrium due to the speed and spring tension. If the mass 2 had been release slowly, the answer could easily be found using the energy forumula(E=1/2*k*x^2), as far as I can understand.

Any bright minds who could spare a few minutes explaining me this?

Help is much appreciated!

Have a nice sunday.

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2. Mar 9, 2014

### tiny-tim

Hi Emilsen! Welcome to PF!

I think "quick release" simply means that M2 starts going down, and M1 starts going up.

So you can use conservation of energy (for M1 and the spring).

3. Mar 10, 2014

### Emilsen

Hi tiny-tim,

I have tried the following equation setup:
E1spring=E2spring+E2kinetic
1/2kx12=1/2kx22+1/2mv2

I used F=kx to find x1 and x2 for mass 1+2 and mass 1.

I then tried the following formula to calculate how heigh the mass 1 went above the E2spring equilibrium:
v2=v1-gs/v1=0, to find s.

Is this the right path?

4. Mar 10, 2014

### tiny-tim

Hi Emilsen!
nooo …

v is irrelevant, since the system both starts and finishes with v = 0