Posted March 18, 2009on:
We just did this lab yesterday and today. It took the whole 50 minute period yesterday plus about 20 minutes today. The feedback I got from the students was really great. We studied torque in the classroom first, solved some problems, then did this lab. They felt that they understood torque after completing the lab. I came up with the lab in the shower in the morning (all of my great ideas and life solutions appear when I’m in the shower) and I wrote the whole thing up in my prep period before their class. So much for planning ahead.
The lab uses a ring stand and support. I have pendulum attachments for ring stands, but a regular ring will work just fine. Using a meter stick, string, and some weights, they first create a balanced system with no net torque. They then calculate the torque in each direction to show it is balance. They do this with two weights and then with three.
Next, they pick a location for one weight and have to determine where the second weight goes to balance the system. They know they get it when the meter stick balances right away. Again, they repeat this with three weights.
Lastly, they move the fulcrum so the stick becomes part of the problem. You can read the details in the lab, I think it’s fairly clear.
My lab sheets are here, feel free to use it as-is or modify them: