Question

Name: Date: CVEN207-Sures2019 In today's laboratory we will learn measurement technigues that will be used in laboratory over the routine calculations. Lastly we will look at how uncertainty relates to measurement, precision and Laboratory # 2 : Measurement and UncertaintyY Introduction semester. We will also examine the use of dimensional analysis and significant figures in performing accuracy. Precision Scientific measurements should be as precise as possible: this means that every measurement will include one uncertain or estimated digit. The number of significant figures you can report will depend on the measuring tool used. For example, the ruler shown in Figure 1 has large marks every 1 cm, and smaller marks every mm. The length of the nail is certainly between 3.7 and 3.8 cm, thus indicating at least 2 significant figures. However, you can add one more digit to your reported value by estimating the value between the lines. Thus, you could report the length of the nail as 3.75 cm, where the last digit represents your "estimated" value. The lesson is one should always try to "read between the lines". A second rule to remember when making measurements is that if the length of the nail was exactly on the 4 cm line, you should indicate the precision to which you can make this measurement by adding zero's to your value and record the length as 4.00 cm The precision of a measurement is often quoted in terms of how inaccurate the estimated digit is. For example in Figure 1 since the sensitivity of the ruler is 0.1 cm the uncertainty would be stated as half that or +/-0.05 cm. The +/-indicates that the measurement could be shorter or longer then the stated value. The 0.05 cm indicates two things, first the number of places past the decimal point it is possible to read (in this case 2) and the precision to which the last digit can be estimated (in this case you can probably distinguish if a length was % way between the two millimeter marks, but cannot guess if it was 0.01 or 0.02). Remember, ALWAYS read between the lines, and report measurements to as many decimal places as ossible, using zeros to indicate additional precision if needed. 2 3 4 5 CM e 1: Using a ruler. Measure the nail with your metal ruler and report the result in cm. Measure the width of a paper in inches and report the result in inches. cy uracy of a measurement or mple, if we measured the density of a sample and then compared the value measured to that d in a reference such as the Handbook of Chemistry and Physics. High accuracy would indicate experimental value is very close to the known value listed in the reference. calculated quantity refers to its agreement with some known value.

Answer 1

Criver, uler 1cm Sensitivity to 3-8cm Jn btweem 3-7 cm Lemgth Nail the Senaitivity O1Cm is As 3-750m mal as bumgth o the the Roumd Sensitivity the hatt axtaindty Now, mctal uler divisions Senritivity 20 OD5 cm betweem 3'75cm lhes nail the hemgth o Precite 3:8cm to Sensisitivity 005 Cm. tme As Uncertainity O05 OO25 cm 2- 3.75+ 0'025 Rownd h hemph hthe Nail the 3.775Cm

divisions suler metal has 64 A be notiad in between it a inch to indh coam meteluler 4 inch dapicted OT) the uler 00 15625 inch Sensitivity omtal 64 betweem ies in the paper Widtth stamdard betweem 0.D7/875 inch tuthea Nalue in 626inches with 0035inuh . bPaner lies in between Stomdard width to 826975 inch 82 671 875 inch 0-615625 inch Here, Sensitivi ty Uncestainity O.0078125 inch Nail the Rounded Tucise hemgth 2. 671 875 +0'06 78125 92 6196875 inches