Maybe I shouldn't have started this blog now, not with everything that's been going on.

In my mechanics class last Wednesday we had the experiment on Coefficient of Friction.

For the umpteenth time I’ll be saying that it is the first time for me to use this equipment that I had my students pass three terms ago.

The pulley was large enough that the string was completely horizontal when attached to the block and completely vertical on the part attached to hanging pan.

The plank also did not have the sandpaper attached to the middle.

For the morning class I also printed out and cut up the pieces of paper where they were going to answer their quiz, and just like last week I had to tell them to put away the one-fourth sheets that they already brought out. So they can become trained after all, it just takes a little more time than I’m expecting.

Not that they get high scores on the quiz now. Considering that with this quiz they just had to guess the number of trials, the weights to be loaded on the block and whether or not the string and the load on the block will be used in all set ups.

At least I wrote the answers to the questions on the board afterwards, which I didn’t erase for the afternoon class, and I gave them the same questions. As far as I know only two of the students in the afternoon class looked at the board to get the answers, and not to all of the questions at that.

The hitch in today’s experiment (as usual) was in the fact that they had exhausted all of their hanging weights for attempting to get the block with the one-kilogram load to move, and it wouldn’t.

Because the original procedure called that even one and a half kilograms would be placed on the block, it had to be scrapped and replaced with 0.25, 0.5 and 0.75 kilograms load instead.

For the afternoon class, I even changed it to 0.2, 0.4, 0.6 and 0.8 kg, because there were supposed to be five sets of trials in the original table and not four (including zero load). The morning class had it just a bit easier because of that.

I also warned them against bumping the table, which would make the block move before it would have otherwise. Same with getting more than three trials and just recording the three values those nearest each other.

There was also the additional dilemma that for the inclined plane the height that they got resulted in an angle that was greater than 45 degrees, and therefore they arrived at a value for the coefficient of friction that was greater than 1, which should not be the case.

Obviously, the only thing I could blame it on was additional friction (bad this time, not good) on the pulley.

Surprisingly though, their graphs were all linear, and were able to provide them with a valid, even if not accurate, value for the slope which is also the coefficient of friction for the horizontal plane.

And that’s Wednesday last week. Tomorrow I’ll start on my Thursday classes after Mathematical Methods 1, then it’s straight to today’s sessions. For now, we’ll give way to the next teacher.