All AP Components Labs

I have nearly finished grading the Section 2 labs and most of them are awful, however much of this applies to reports from both classes. Many have no data on the hanging mass used to find Fg// or the reading of FN using the scale. The purpose of the lab is to see if using Fg cos theta vertical for Fg// and Fg cos theta horiz for Fgperp works. How are you to compare your calculated values to the real values if you do not record or show the real values? Just because you did not receive a nice, pre-made data table which had blanks for you to fill in, doesn't mean you were not responsible for recording data.

Some of you continue to leave out the calculations you made to find values. You must include at least the equations you used and all the data used to arrive at your predicted or expected or ideal values and your value calculated from measurements. For example Fg// predicted = Mcartg x h/L and Fg// actual = Mhanging x g.

Many of you used the cos, h/L, to find the angle using cos^-1 on your calculator. You then found the cos from cos of the theta you found from the cos^-1. This shows a level of incomprehension that is alarming. You found the angle from the cos and then found the cos from this angle. I guess you have a lot of time to waste. [By the way, you should know that a^-1 x a = 1 ]. You didn't need to find the angles since h/L = cos theta vertical and b/L = cos theta horizontal [or use 1- (cos theta v) ^2 = (cos theta h) ^2]. Your depedence on your claulators for finding everything is scary.

Many of you talk about the spring scale not giving an accurate reading for Fg//. Well, we didn't use spring scales for Fg// did we? We used hanging masses and they gave very accurate readings as long as you counted the masses properly and didn't have anything jamming your pulleys.

You will have until next Monday, 11/9 to correct these disasters, but this will be the last lab for which I will allow this kind of resubmission. Many of you will have to re do the lab this week becuase of your failure to record the data.