Assign and grade labs

Lab 1 · falling ball. Value: the reported g is within the tolerance of the student’s true g; the tolerance depends on the timer the result came from. Uncertainty: what a perfect experiment would measure (the true g, lowered by air drag on that planet for that ball and those heights) lies within 2 × the reported uncertainty, and the uncertainty is no more than the allowed percentage of g. Method: the required number of heights each have the required number of drops, with one ball and one timer. Explanation: the first answer to the question chosen from the student’s data is correct.

Lab 2 · projectile. Value: the reported g is within the tolerance of the true g. A metre stick left on the front edge of the bench (parallax trap) makes g about 15 % low, so this check fails. Uncertainty: what perfect clicks would measure with the student’s launches lies within 2 × the reported uncertainty, and the uncertainty is no more than the allowed percentage. Method: the required number of launches, each with enough tracked points in the fit and all four graphs fitted with the right models (x–t line, y–t parabola, v_x–t line, v_y–t line), from at least two different settings. Explanation: the first answer is correct (about parallax when the trap is on, otherwise about why v_y scatters more). Students may leave bad marks out of a fit, giving a reason in their notebook; the notes column shows how many points each launch left out.

Lab 3 · spring. Value: for every spring reported, k from the oscillations is within the tolerance of that spring’s true k. Uncertainty: each spring’s true k lies within 2 × the reported uncertainty, and the uncertainty is no more than the allowed percentage. Method: the required number of springs each have the required number of loads read on the stick and timed, a k from the stretch as well, and every stopwatch timing covers at least the required number of oscillations (the motion sensor needs no count). Explanation: the first answer is correct (about the hanger when the hanger trap is on, otherwise about why the T²–m line does not pass through the origin).

A code is refused if it was edited (checksum), damaged in copying, made for a different assignment, or made for another lab. If a student pastes more than one code, the last one counts. Identical data under two IDs is flagged. The checksum stops casual editing, not a determined student who reads the page source.