Finding the spring constant while stretching and compressing

[Eric0]

Homework Statement

I have a physics lab that I'm just not making any progress on. For this lab my group used a 314 g cart. Two springs were used, both attached to the cart, and one being stretched the other compressed. The cart was then ran horizontally and it's velocity was found.

I want to find the the spring constant for each trial and then average it. I have the velocities for each trial of the cart after stretching/compressing. The three velocities of the cart after being attached to the stretched or compressed string in m/s are 1.18, 2.68, and 3.65. For the compression trials the velocity in m/s was found to be .2, .7, and 1.0.

Natural length of the stretched spring is 6 cm and the compressed 8.4 cm.

Homework Equations

The Attempt at a Solution

I tried to used the formula given: k= (1/2mv²)/x with x being the distance stretched/compressed. The values I got were kind of funky. I'm thinking I need to use kinetic or potential energy here.

 

[The Liberator]

I tried to used the formula given: k= (1/2mv²)/x with x being the distance stretched/compressed. The values I got were kind of funky. I'm thinking I need to use kinetic or potential energy here.

Hi Eric,

I think that I might be very wrong here, but I am looking at one of the more basic spring equations here; elastic potential energy: U_s = 1/2kx²

…And if it is re-arranged, I cannot find that it turns into one of the equations that you are using here. I might very well be wrong, and I am sure that someone else will be able to help you properly, but I think you need to check you equations and re look at it in a different way.

Liberator.

 

[nlightner]

Hello,

Thank you for sharing your lab and the data you have collected. It seems like you are on the right track in trying to find the spring constant for each trial and then averaging them. However, I would like to clarify a few things before providing further guidance.

Firstly, it would be helpful to know the units of your velocities. Are they in m/s or cm/s? This will affect the units of your spring constant. Additionally, can you provide the mass of the cart? This information is necessary to calculate the kinetic energy in the formula you mentioned.

Secondly, it would be helpful to know the initial and final positions of the cart for each trial (i.e. the distance the spring is stretched or compressed). This will help in calculating the potential energy in the formula.

Once you have clarified these details, you can use the equations for potential and kinetic energy to calculate the spring constant. Remember to use consistent units throughout your calculations.

I hope this helps and good luck with your lab!