# Lab Practicum with a Spring

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1. Nov 15, 2008

### marc16250

The purpose the lab is to get a 1kg mass on a long spring (approx 3meters) to touch, without cracking, the top of an egg. To do this, we need to solve for the height needed to drop weight from.

I'm not sure how to solve the problem and I have been using the following formulas:
F=kx
E=1/2kx^2

So far, I have calculated the spring constant by using different masses and recording the change in distance. I got K= 3.78N/m. I have measured the height from the top of the spring to the top of the egg, and i measured the height from the bottom of the weight to the top of the egg. Now, I am not sure how to go about solving the problem.

Can anyone give me a hint, or solve the problem?

*I attached a sketch of the situation (note that all measurements are to the top of the egg and not the floor)

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2. Nov 15, 2008

### LowlyPion

Welcome to PF.

If you have derived your k for the spring, then you know how much energy the spring can absorb. So isn't it simply a matter of knowing how much below the point that the weight hangs that it has to go? Knowing that gives you the energy which you can supply by dropping the weight from a height above the rest point.

m*g*h = 1/2*k*x2

3. Nov 15, 2008

### marc16250

that makes sense....thanks

4. Jan 22, 2009

### Punjabi.Sher

I have a similar lab practicum. Basically there is a certain mass on a spring and we need to find the height it must be dropped from.

I dont know what heights I should use. I also dont understand how to find the spring constant. Can someone please help me?

EDIT: I have not posted any work because we have not received any information on this lab. So tommorow we are actually going to do the lab, but I am preparing how to do it. So I just want to know how one would solve this kind of problem. Like what measurements should I take and what steps should I follow. Thanks.

5. Jan 22, 2009

### LowlyPion

The method described in the OP for determining k is ok. Simply employ different static weights and note the displacements. That should provide you with enough points to determine the extension per force across your range of interest. That would be your key unknown that needs determining. (Be sure and develop an error range for what you determine.)