Presentation on theme: "Measurement Notes From pages 21-25 in the text Honors Intro Physics Friday, Sept. 4 th."— Presentation transcript:
Measurement Notes From pages 21-25 in the text Honors Intro Physics Friday, Sept. 4 th
Making a Measurement Accuracy: How close the value is to the actual or accepted value of the quantity measured. Precision: the degree of exactness to which the measurement of a quantity can be reproduced.
Displaying a Measurement Significant Digits: the digits in a measured value that are valid, due to the precision of the measuring device. The last digit in a measurement is estimated as it falls between the smallest divisions on a given scale. Ex. You estimate tenths of a millimeter with a metric ruler.
Significant Figures 1.Nonzero digits are always significant. 2.All final zeros AFTER a decimal point are significant. 3.Zeros between other significant digits are always significant. 4.Zeros used solely to space the decimal point are NOT significant. (i.e. 0.008)
Practice Sig. Fig.s How many Significant Figures does each item have? 1.6.201 cm 2.302.4 hours 3.274,000 miles 4.75.00 mm 5.0.007 060 kg
Calculating with Sig. Fig.s A calculated answer can not be more precise than the least precise measurement used in the calculation. There are different rules based on the type of operation used in the calculation. Adding and Subtracting: Look at the term with the fewest decimal places, round all answers to that many decimal places. i.e. 2.4 cm + 1.375 cm = 3.775 = 3.8 cm
Cont. - Calculating with Sig. Fig.s Multiplication and Division: Look for the factor with the least significant figures and always round your answer to that many significant digits. i.e. 2.4 cm × 6.75 cm = 16.2 = 16 cm 17 ÷ 3.0 = 5.66666667 = ________?
Now Practice…. Each student will perform the following measurements and record their work in a neat and organized single page report. Measure the surface area of a classroom table top to the highest level of accuracy and the greatest precision allowed by the tools available. Include in your report: Purpose, procedure, data, calculations, final answer, and a discussion demonstrating what you understand about the accuracy and precision of the value you are submitting.
Quick Quiz Problems Calculate the following answers using the correct number of Significant Digits 1)132.76 + 32.899 + 345.0076 = _______ ? 2)3004.56 X 2.0078 = _______ ? 3)23.878 ÷ 7.555 = ________ ? 4)398.475 – 29.99 = ________ ? 5)(3.4 + 2.3 + 3.7) / 0.375 = ________ ?
Quick Quiz Answers Calculate the following answers using the correct number of Significant Digits 1)132.76 + 32.899 + 345.0076 = _510.67__ ? 2)3004.56 X 2.0078 = _6032.6_ ? 3)23.878 ÷ 7.555 = __3.161__ ? 4)398.475 – 29.99 = __368.49__ ? 5)(3.4 + 2.3 + 3.7) / 0.375 = ___25__ ?