PHYSICS · Multi-part · A Level · Physics · Measurements and their errors · Measurements and their errors
Problem
Two different school laboratories, A and B, determine the acceleration due to gravity g at the same location. Each lab performs five repeat measurements and reports the following values (in ms−2):
Lab A: 9.79, 9.83, 9.80, 9.82, 9.81
Lab B: 9.90, 9.89, 9.91, 9.88, 9.92
The standard accepted value at that location is 9.81 ms−2.
Study the data and answer the questions below, stating all final results to the correct number of significant figures.
(i) Calculate the mean value of g obtained by each laboratory.
(ii) For each laboratory, determine the absolute error and the percentage error of the mean with respect to the accepted value.
(iii) For each laboratory, calculate the mean absolute deviation of its five readings from its own mean value and quote it as a measure of precision.
(iv) Decide which laboratory’s result is more accurate and which is more precise. Give a clear quantitative justification.
(v) Suggest two possible experimental factors that could account for (a) the lack of accuracy and (b) the lack of precision observed in the data.