# Day 29: Spring Lab Debrief

*College-Prep Physics:* Yesterday, students designed their own experiments to determine the relationship between the stretch of a spring and the force applied to the spring. Today we shared out our results.

This year, I chose to use 2 different springs: one with a pre-load (red) and one without (green). My goal is to drive home that not all trends will go through the origin. Some groups still tried to fit a trend through the origin, though. Looking back, if I had been monitoring groups better, I would have asked those groups to go back and take more data for small stretches….hopefully continuing the linear trend down to the y-intercept.

##BFPM

*NGSS Science and Engineering Practice #4: Analyzing and Interpreting Data
NGSS Science and Engineering Practice #5. Using Mathematics*

How do you get a spring with a preload on it? Would this be using a force gauge that is pre-loaded? Are the students explicitly aware that there is a pre-load?

Thanks!

Springs that are very tightly coiled have preload. We used regular spring scales to measure force. No, the students didn’t know about pre-load. I wanted them to determine on their own if their trends needed y-intercepts.