Pulley Lab – Mechanical Advantage

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:

pulley-lab-rev-c2

pulley-lab-data-sheet1

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.