1 / 9

September 20, 2010 – “F” Day

September 20, 2010 – “F” Day. Objective: To understand the importance of measurement accuracy in calculations Do Now: What is the density of a 45kg object with a volume of 15L? What is the volume of 3.5g of an object with a density of 12g/mL?. Today: Do Now Significant figures tutorial

chip
Télécharger la présentation

September 20, 2010 – “F” Day

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. September 20, 2010 – “F” Day • Objective: • To understand the importance of measurement accuracy in calculations • Do Now: • What is the density of a 45kg object with a volume of 15L? • What is the volume of 3.5g of an object with a density of 12g/mL? Today: Do Now Significant figures tutorial CW/HW – Read/prepare for Density Determinations Lab

  2. September 21, 2010 – “A” Day • Objective: • To understand the importance of measurement accuracy in calculations • Do Now: • What are significant figures? Why are they important? Today: Do Now Go over significant figures notes/problems CW/HW – Read/prepare for Density Determinations Lab

  3. Significant Figures Tutorial • Go to http://moourl.com/sigfig • Complete the tutorial and take DETAILED notes • Complete Significant Figures Practice Problems • HW – Read/Prepare for Density Determinations Lab

  4. Significant Figures • All measurements are approximations--no measuring device can give perfect measurements without experimental uncertainty • By convention, a mass measured to 13.2 g is said to have an absolute uncertainty of 0.1 g and is said to have been measured to the nearest 0.1 g. • In other words, we are somewhat uncertain about that last digit —it could be a "2"; then again, it could be a "1" or a "3". A mass of 13.20 g indicates an absolute uncertainty of 0.01 g…

  5. What is a "significant figure”? • The number of significant figures in a result is simply the number of figures that are known with some degree of reliability. • The number 13.2 is said to have 3 significant figures. • The number 13.20 is said to have 4 significant figures.

  6. Rules for deciding the number of significant figures: • (1) All nonzero digits are significant: • 1.234 g has 4 significant figures, • 1.2 g has 2 significant figures. • (2) Zeroes between nonzero digits are significant: • 1002 kg has 4 significant figures, • 3.07 mL has 3 significant figures.

  7. Rules Continued • (3) Leading zeros to the left of the first nonzero digits are not significant; such zeroes merely indicate the position of the decimal point: • 0.001 oC has only 1 significant figure, • 0.012 g has 2 significant figures. • (4) Trailing zeroes that are also to the right of a decimal point in a number are significant: • 0.0230 mL has 3 significant figures • 0.20 g has 2 significant figures.

  8. Last Rule • (5) When a number ends in zeroes that are not to the right of a decimal point, the zeroes are not significant: • 190 miles has only 2 significant figures, • 50,600 calories has only 3 significant figures. This last rule is a major reason why scientists use scientific notation! • 5.06 × 104 calories (3 significant figures) • 5.060 × 104 calories (4 significant figures), or • 5.0600 × 104 calories (5 significant figures)

  9. Multiplying and Dividing • Answers must contain the same number of significant figures as in the number with the least amount of significant figures • Try This:

More Related