Objective: Differentiate between accuracy and precision.

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Presentation transcript:

Objective: Differentiate between accuracy and precision.

 Exact number – a number that has been determined as a result of counting.  The main emphasis of mathematics.  Approximate numbers – inexact number resulting for the measurement process.  Usually how most technical data are collected  Better the measurement device, the better the measurement.

 The accuracy of a measurement refers to the number of significant digits.  Significant digits – the number of units we are reasonably sure of counting.  They include all the known digits recorded from an instrument plus one estimated digit.  The greater the number of significant digits, the greater the accuracy.

Determining Significant Digits 1. All non-zeros are significant m has four significant digits (measurement indicates 1564 tenths of meters) 2. All zeros between significant digits km has five significant digits (measurement indicates hundredths of kilometers) 3. In a number greater than 1, a zero that is specifically tagged, such as by a bar above it, is significant 230̄ 000 km has three significant digits (measurement indicates 230̄ thousands of kilometers)

4. All zeros to the right of a significant digit and a decimal point are significant cm has four significant digits (measurement indicates 8610̄ hundredths of centimeters) 5. In whole-number measurements, zeros at the right that are not tagged are not significant m has two significant digits (25 hundreds of meters) 6. In measurements less than 1, zeros at the left are not significant m has three significant digits (752 hundred- thousandths of a meter)

 Scientific notation  The first factor indicates the number of significant digits.

 Precision – refers to the smallest unit with which a measurement is made, that is, the position of the last sig. fig.  km has a precision of 1000 km  g has a precision of g  s has a precision of s  12.3 m has a precision of 0.1 m