Measurements in Experiments Chapter 1 2 Numerical Measurements
- Slides: 11
Measurements in Experiments Chapter 1 -2
Numerical Measurements n Are used to perform science experiments. n Gives number and dimensional unit ¨ Example : 5 m (meters), 15 kg (kilograms), 25 s (seconds)
Dimensional Units n SI (Systeme International) is the standard measurement system for science. n Three basic dimensions are length, mass, and time. n The units for length, mass and time are meter (m) , kilogram (kg), and second (s).
SI Prefixes n To accommodate the broad range from very large to very small measurements, SI uses prefixes.
SI Prefixes n Using these prefixes we are able to build conversion factors from any equivalent relationship. ¨ n 1 mm = 1 x 10 -3 m When converting, both dimension and units MUST AGREE. ¨ Example: m (length) ≠ kg (mass)
Sample Problem 1 A n Open Books to pg. 14
Accuracy and Precision Careful measurements are very important in physics. n Accuracy – how close to true value n ¨ Problems with accuracy are due to error ¨ Human error , method error, instrument error n Precision – how exact ¨ Problems with precision are due to limitations ¨ More decimal places, more precise (1. 325 m is more precise than 1. 3 m)
Significant Figures n Used to indicate precision.
Calculating with Sig Figs
Rules for Rounding
Guided Practice n Section Review Pg. 19
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