Alzar School | 31.10.13

I found an old car strut (a big heavy spring) in Cobquecura and immediately knew I had to use it for physics class. I brought it to class and asked the students to use Hook’s Law and measure the spring constant and have fun with the information.


A spring constant is a relationship between the amount of force applied to the spring and how far it stretches or compresses. It essentially reveals how strong or stiff the spring is. With this information predictions can be made about our fellow classmates and teachers. In particular, the physics students can predict their peer’s weight.

The task offered a genuine scientific experiment, and the students gobbled up the task. They used their whitewater safety webbing to sling the spring, and then each of us stepped into the sling and stretched it out. Then we sat on the spring and measured how far the spring compressed.


By knowing each of our weights and measuring the stretch and compression of the spring they could calculate the spring’s constant. Then they instructed other instructors and students either stretch it or compress it with their weights. A simple measurement and the students predicted each of the outsider’s weight.

The students’ predictions were very close to actual weights. When Ellie stretched the spring the prediction was about 10 lbs. too heavy, and when Estée compressed the spring the prediction was about 10 lbs. too light.

Calculations and predictions.
Calculations and predictions.

It’s always very exciting for the students when physics works in the real world. Especially in when it works in S. America!

-Sam Goff, Physics Instructor