Definitions and Examples Accuracy Closeness of a measurement to the accepted value Precision Reproducibility of a measurement Physics 104

Significant Digits All measured digits plus one estimated digit Read the smallest division on the instrument and then estimate one more digit 3 3 2 3.21 has ___ significant digits. The ___ and ___ are measured and the ___ is estimated. Eight and ¼ meter long string should be reported as ____ m or ____ m. 1 8.2 8.3 Physics 104

1 Y 3 5 Review In a measurement, how many digits are estimated? Is the estimated digit significant? A measurement 2.45 m has ___ significant digits. The ___ is the estimated digit. 1 Y 3 5 Physics 104

Convert 2.54 m to … km Mm dm cm mm μm 0.00254 km 0.00000254 Mm 25.4 dm In each, the ___ and the ___ are measured and the ___ is estimated. The purpose of the zeros is to act as decimal place holders. 4 Physics 104

8600 m = 8.60 x 103 m A zero can be a measured digit. A zero can be an estimated digit. Zeros are not significant when they are place holders only. Significant digits examples 83000 km 0.2341 g 0.000015 s 56.08 m/s 8.3 x 103 cm 8.30 x103 cm 132.00 g/cm3 Cover up the zeros. Does the magnitude of the number change? Do zeros disappear when in scientific notation? To show that a place holding zero is significant, put a bar over the zero. 8600 m = 8.60 x 103 m Physics 104

Problem Set #1 1.080 x 10-4 kg 99000000 707000 m/s 0.00025 s 6.0 x 10-4 m3 Physics 104