Pulley Lab – Mechanical Advantage
Posted March 19, 2009on:
I’ve been doing this lab for a number of years, but it needed a make-over. I did that today, it’s beefed up a little and I added a data sheet. I’ve gotten away from the lab notebooks because they are just too hard for me to collect and take home, and I never seem to be able to grade at school. I’ve headed towards more of a “min-lab” format that I read about in The Physics Teacher a year or two ago. This has greatly cut down on my grading, which allows me to do more lab and hands-on work, which gives me more to grade. Somewhere in there we reach equilibrium.
This lab uses two double pulleys, some mason line, a ring stand and ring, spring scales, a meter stick and a weight. I like to use a 1 kg weight. It’s heavy enough that they can feel the difference when the pulley helps out, but not so heavy that everything is falling over. I found it helpful to have two or three different size strings. The short string for the first three configurations is about a foot long. They then switch to a second string that is four or five feet long. I would suggest you play with the lab and then make up the appropriate length strings. I like the pink mason line, it’s easy to see from across the room, so I can tell what’s going on at every work station. It’s also easy to find when things are misplaced.
Here is the lab and data sheet:
I would love suggestions and ideas to improve this lab. I’m still not thrilled with the overall lab, but it’s the best I’ve been able to do so far.