AP a=F/M Lab Reports

Your lab reports continue to range from amusing to exasperating. Some of you persist in plotting the wrong variables on the vertical and horizontal axis. Avs B means A on the vertical, B on the horizontal. You should have plotted a vs 1/mass. If you did the reverse, you must fix this. Nearly all of you said confidently that the slope was the force (including those who plotted 1/mass vs a for which the slope is 1/force). However only one of you bothered to actually calculate the slope and compare it with the force, which is the only way you could demonstrate that a =F/m.

It is not clear that most of you realize what the force causing the acceleration was in the two runs, so that you know with what you should compare the slopes once you have calculated them. Fix this. Calculate slopes, compare them with F and show the calculation and discuss the results and the reasons for them in your conclusion. You need to think and then demonstrate that you have thought, learned, and understood.

The last question about why the line of best fit intersects the horizontal axis at some point to the right of the origin elicited many very interesting, but few correct explanations. Think about the relation between a and 1/mass. If F = something greater than zero what does 1/mass have to be for a to equal zero? If a = 0 and 1/mass was not zero (i.e. the mass of the system was not infinite) what does that say about the net force on the system? If the net force is zero when the force of gravity was applying a force on the system what other force is probably present? 10 additional points of credit on the lab if you can identify it and calculate it for at least one run ( not trial). Again show the calculations and discuss the results and the reasons for them in your conclusion. You need to think and then demonstrate that you have thought, learned, and understood.

If you have not turned this lab in, or any other outstanding lab or resubmittal , do so by the Wednesday. All late labs do lose points