Work-energy

Ryne Saxe has heavily revised the Work-Energy lab, with great results. He's re-written the writeup, and come up with some teachers notes as well. His work can be found here.

Plane & Curved Mirrors

Terrance Gibson ran the plane & curved mirrors lab, and found it to be in good order. Some comments:

The reflection – plane and curved mirrors is an experiment to better understand how rays are reflected by determining the focal length and radius of curvature of different types of mirrors. The setup of the experiment is very straightforward meaning easily to follow and not much equipment to use at all. However I prefer doing the experiment in a dark room to see the light rays better. I think if you try doing this lab with different color paper instead of white paper it might work better, you might not have to turn the lights off. But, all in all, this is a wonderful lab to continue doing to understand how rays are reflected, using a protractor, and ruler to obtain the angles of the rays.

Friction lab (kinetic)

Eric, Chris and I may have hit on a way to do the friction lab with reproducible results -- it worked pretty well today with a variety of different sliding objects. The basic idea was to slide a block on a flat track and let it go, and use the ultrasonic position sensor to measure its velocity decreasing with time after you let go. The slope of v(t) should give you (mu)*g. We tried it with aluminum and wood blocks today of various sizes, and it was fairly reproducible. If we continue to have good luck, it might be a good alternative to the varying the angle of an inclined plane -- kinetic friction seems more reliable than static, and doing a slope measurement averages out a lot of the uncertainty. We'll see if it continues to give reliable results ...

One objection might be that we are measuring kinetic instead of static friction, but myself I don't see this as a big problem.