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Measurement & Uncertainty

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Spacer This lab is an introduction to measurement and uncertainty. It discusses random and systematic errors, the meaning of uncertainty, the use of significant figures and standard deviation to express the uncertainty in a measurement, the use of histograms and bell curves to determine when sufficient data has been collected and the use of slopes of straight line plots to make a computation for the value for a physical quantity.

The lab is divided into two parts:

1. The Foucault Pendulum. Students use a stopwatch to measure the period of the Foucault Pendulum in Fairchild. The period is measured in three ways: (1) timing a single measurement, (2) making 20 (or more) measurements of a single period and using the average as the measured value and (3) timing 10 periods and dividing the total time by ten to get a value for the period. Students are then required to state which method gives the most precise period and to justify their choice.

2. The Wall. Students use a metric tape measure to measure the length of a cinder block in the wall of their lab room. They use methods similar to those employed in part I, but this time they use standard deviation to express their uncertainty. They also measure the position of ten or more blocks along the wall, plot this data and use the slope of the plot to get a value for the length of a single block. An estimate of the uncertainty is determined by plotting high and low "worst "lines through the data. Students are then required to state which method gives the most precise length and to justify their choice.

Course Level

Introductory: P3, P13, P15

Student Handouts


Number of set-ups available: 1

Per lab station:

1 clear plastic ruler
1 stopwatch
1 metric tape measure



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